Charles and I were at a party recently when an acquaintance of his, Steve, started talking about a woman he'd slept with on a first date and described her as "a bit of a slut". I went nuclear. While I don't agree with calling anyone names, by his own logic he'd been a "slut" as well.

"Men are programmed to spread their seed," he said, "but women should be monogamous because they can only produce one egg at a time."

He mentioned a study that apparently revealed "evolution has not adapted women to having casual sex" because some women reported feeling "used" afterwards. I think women would feel less remorse if there were fewer idiots like Steve out there. Even Darwin knew females weren't monogamous.

Professor Tim Birkhead wrote in his book Promiscuity: An Evolutionary History of Sperm Competition and Sexual Conflict that Darwin was aware of instances in which females received sperm from more than one male. But Darwin, being a Victorian, preferred writing about promiscuity among plants than human females. Sleeping around may benefit women because of sperm competition – even if that involves sex with several different men in quick succession.

Men do flirt with me more when I'm in a new relationship. I thought that was a reaction to my exuding confidence and happiness. But maybe there's something more primal going on. Biologist Olivia Judson writes that men shown explicit pictures of a woman with two men (potential rivals) produce a higher proportion of swimming sperm than men shown explicit pictures of three women.

I unintentionally had a chance to test the love-rival theory when I met Charles in town for a late lunch, which ended with us polishing off two bottles of wine and slipping back to his flat to eat dessert off each other. With no time to shower, I emerged, legs still shaking, en route to my next meeting. I met my TV producer friend for coffee, and he was very flirtatious, and asked if I'd changed perfumes. That afternoon, five men gave me their phone numbers. I binned them. I'm choosing to be in a committed relationship. Love is more than an evolutionary arms race.

But being monogamous is a choice for both sexes, because at the end of the day we all have animal instincts. Maybe fear of being judged is also part of evolution. I read recently researchers found that female chimps wanted sex with as many males as possible without other females finding out. Hmm.

The row with Steve hotted up when he used the word "whore". I "accidentally" dumped a glass of red wine all over the crotch of his very expensive suit. I felt horrible afterwards. The bottle cost £23.

I enjoyed living vicariously through Tango magazine's story on female happy endings at massage parlours [via Salon]. Men have been going to dodgy spas behind unmarked doors for 'quick releases' for ages, but the female version has always been taboo--until now. “It’s all about giving the right signals," said one female veteran. “Initially [the masseur] kept it very clean, but I was really turned on, and I let him know it by moaning and saying how good it felt. He started slowly touching my thigh...one thing led to another and he ended up finishing me off, which was great.”

I found the tale arousing, since I've often had my mind wander during a massage but never dreamed of taking things further. But I would never have the courage to ask - and since women don't get erections, according to the a male masseur quoted in the piece the signals are harder to read. Tango sent a reporter undercover (to high-end spas, not back alleys), and she ended up scoring with 'Tron', a very fit therapist. They kissed, but didn't go all the way, as she writes: "I considered giving him a blow job, but then I was like, 'I'm paying for this!'"

A friend recently suggested that I try Cosmic Ordering, which involves writing down your wishes on a piece of paper and waiting for the cosmos to come through.

I was sceptical, but aided by two bottles of wine at dinner, I began my list with, "6ft-plus, emotionally mature, supportive of my job, kind, generous, loving, intelligent, 10-15 years older, massive penis!" (After all, this was a wish list!)

I crumpled the note in a drawer, passed out on my bed in my clothes, and forgot all about it. Exactly two days later, the universe delivered Charles, who ticked all of my boxes. He really is the perfect man on paper.

I was actually feeling at peace for the first time in ages, until my friend Victoria asked me how old he is, and I replied, "44".

"Wow, all of your boyfriends are nearly 15 years older. Have you ever considered why that is a critical item on your list?"

I'm used to my friends teasing me that my last name should be "Zeta-Jones", because I often date men at least at decade older than me.

I've told myself over the past few years that my attraction to older men was because they had more life experience. Besides, they were the ones who tended to ask me out!

More recently, I've realised that it may be a bit more complicated than that. I hate to admit it, but one of the reasons that I date men who are older is because I somehow think that, eventually, they will be less likely to leave me for someone younger.

Some of my first memories are of my dad leaving my stunning, university-educated mum, who adored him, for a younger model, his secretary. The kicker was that she wasn't even a more attractive model. It really was the equivalent of trading in a vintage Aston Martin for a used Fiat Punto.

I have never admitted this to anyone, but every time I see a friend marry a man his or her own age, a part of me is terrified for them. No matter how lovingly the young man looks into their eyes, I can't help but think: "They are happy now, but how will she feel in 10 years when he starts eyeing up the teenage Russian nanny?"

Of course, I know that my logic is flawed, and I don't judge all men this way. I should know better than anyone that when it comes to love, older doesn't always equal wiser.

Case in point: my ex-boyfriend was a decade older than me, and he broke my heart anyway. I've met 25-year-old men were ready to start families, and 40-plus Peter Pan clones who were still wearing trainers and hanging out at nightclubs.

My friend Michael is more brutal. When he found out I'd been getting texts from a 53-year-old, he said: "A man can be a cad at any age. If you think that dating a guy with one foot in the grave will insulate you against pain, you're crazy."

On our next date, I told Charles the story of my dad. He gave me a hug, reminded me that people are attracted to other people for all sorts of complicated reasons, and encouraged me not to overthink things as he carried me to the bedroom.

I'm not sure if my cosmic order will equal ultimate happiness in the end. But either way, the universe definitely delivered in the trouser department!

A story in today's Indy says that three members of the Welsh assembly have disclosed in a questionnaire that they have been raped, and none of them reported the crime to police. Even more shocking is the larger study by Amnesty International and NUS Wales was that, of more than 700 students, a third believed a woman was totally or partially responsible for being raped or sexually assaulted if she was drunk or had been flirtatious.

It is horrifying to me that women can still be accused of "asking for it" because they had too much to drink or wore a short skirt.

Drinking may increase a chance of rape, but that's true for both men and women. In fact, studies show that it's more likely that a rapist has been drinking than his victim - and that drinking alcohol may cause men to reinterpret a woman's behaviour as a sign of her desire to have sex with him.

Everyone needs to be responsible for his or her own personal safety, but while we constantly remind women to not drink too much, why aren't we telling men not be too smashed to make sure that they have consent?

Most depressing: if our politicians are afraid of reporting a crime for fear of being publicly shamed and having their sexual histories called into question, what chance do the rest of us have?

According to the Telegraph, a new study shows that women still regret one-night stands more than men: apparently, 80 per cent of men had overall positive feelings about the experience compared to 54 per cent of women, and men were also more likely than women to want their friends to hear about it.

But, while explaining that women have not adapted to meaningless sex because it does not suit them at this stage in evolution, the paper didn't tell the whole story.

Professor Anne Campbell from Durham University was quoted as saying:

"In evolutionary terms women bear the brunt of parental care and it has been generally thought that it was to their advantage to choose their mate carefully and remain faithful to make sure that their mate had no reason to believe he was raising another man's child."

But Professor Campbell went on to say (and not reported by the Telegraph):

"Recently biologists have suggested that females could benefit from mating with many men - it would increase the genetic diversity of their children and, if a high quality man would not stay with them forever, they might at least get his excellent genes for their child."

Funny how any story about how women enjoying multiple partners as part of evolution doesn't usually make the news. Except when we are talking about earthworms and chimpanzees.

I had always thought I would love two men fighting over me. Until it happened, that is. My evening started at a Hedge Fund Fight Nite, a boxing event in aid of the charity Operation Smile. The room was full of City boys lacing up their gloves, and I was seated close enough to the ring to feel the blood spatters.

Long before charity bouts existed, men have been clubbing each other in front of women. Researchers recently learnt of early man's wooing technique after they found prehistoric remains in Germany that indicate men executed love rivals in order to steal women from neighbouring tribes.

Meanwhile, I'm fighting my own battles with men who seem to have an overabundance of testosterone. Liam has broken up with his girlfriend, and taken me on two dates. It's been amazing, but I've finally learnt my lesson about taking things slowly with men who seem too good to be true, despite my raging hormones. So I told him, sincerely, that I want us to take things slowly, and he now thinks I'm seeing someone else. I was starting to worry that his jealousy might be a bit irrational.

At the charity event, my favourite was a diminutive but totally fit boxer known to his friends as T-Bone. Afterwards, he invited me to join his friends for a drink at Movida. He may have lost the fight, but had impressive stamina, and a great sense of humour – not to mention a body like a work of art.

Instead, I met up with my friend Michael at a karaoke bar, while fending off texts from Liam asking where I was. Finally, I asked him to join us – and when he arrived, was unimpressed to see that I was with an all-male crowd.

"Mate, you seem a bit paranoid," Michael said. "What's the problem?" He was teasing, but Liam was enraged.

We started to get into a stupid argument about my male friends, and I pointed out that the only reason he was so freaked out was because he'd tried to cheat on his own girlfriend. That was when Liam shoved me backwards, and it all kicked off.

Suddenly, over the strains of "Sweet Child O' Mine", one of my closest friends and my new crush were rolling around on the floor. It wasn't exactly Ricky Hatton versus Lennox Lewis. And it wasn't sexy – just stupid, and scary.

I tried to step between them, and ended up hitting my head on the drink trolley. At that, they stopped fighting, and we got some ice for my eye. The wound was only superficial, but the damage to my budding relationship with Liam was done.

At the end of the day, the fighting spirit has to be balanced with courtesy and sportsmanship.

So T-Bone, if you're reading this, I wish that I'd taken up your invitation to Movida. And I can't believe that after a boxing match and bar fight, I was the only person to end up with a black eye.

My new book cover!!!

This is for everyone who has emailed me asking what happened next after 'Sleeping Around' ended... and in my new book, 'Breaking The Rules', I promise to answer all your burning questions, including: Did I go through with the wedding? What happened with my new boyfriend (Hint: It's definitely NOT smooth sailing!)? From the thoughtful soul-searching (Is the true path to 'happily ever after' through lifelong monogamy or unbridled hedonism?) to further sexual exploration (useful techniques for female ejaculation), I really tried to leave no stone unturned. It's published by John Murray on May 29th.

I've always harboured a secret fantasy about playing detective, and hooking up with a spy. So I was very excited to have the wine to meet Sir Richard Dearlove, former head of MI6 and now Master of Pembroke College. He's a real-life version of Daniel Craig's James Bond, but a bit more refined and greyer.

At a drinks reception in Cambridge, we were chatting about the town's cycling culture, but all I could think about was whether the hands that were wrapped around his wine glass had ever throttled the life out of someone.

I had the same reaction with M, the very fit security consultant who's been helping me iron out the details on surveillance for my third book, a murder-mystery. He's been showing me all of the hi-tech gadgets he works with, and I'm loving it.

I was at my weekly pole-dancing class with my girlfriend Amy and a mutual friend, Angie, telling them about M's pinhole spy cameras, when Angie blurted out that she suspected her husband, Tom, was having an affair. "Would you find out for me, Cat?" she asked. "I was going to hire one of those honey trap agencies, but this would be so much simpler, since I know that he's into tall brunettes. Please? You would be saving me a fortune."

I had some reservations, but Angie and I agreed on the ground rules. I would stick to polite conversation only, with absolutely no sexual overtures.

So four days later, I found myself standing outside Monument Tube station, holding a crumpled photograph with a micro-cassette recorder in my handbag, sweating profusely. I hadn't wanted to wear anything revealing, so I'd chosen a high-necked, ruffled, white maxi dress that was more Minnie Mouse than Mata Hari.

Angie had phoned Tom, so I knew which bar he was in. I approached him with a wide grin on my face, and coolly asked if he was Roger.

"No," he replied, laughing, "should I be?" I noticed that he wasn't wearing a wedding ring. Bastard.

"It's just that I've been stood up," I said. "Would you mind if I sat with you guys until I figured out what was going on?"

I told Tom that I was a flight attendant, and he made a lame joke about the Mile High Club. I asked him if he was married, and he got a sad look on his face and told me that he was a widower, and "didn't want to talk about it". Not only was he planning to cheat on Angie – now he was killing her off!

When he put his hand on my knee, I could feel the bile rising in my throat. So I told him that I would meet him later, in his hotel, and jumped up, only to have the contents of my handbag, including the recorder, spill out. I thought I'd been rumbled, but collected myself and got the hell out of there, giving him strict instructions not to call me until he was "in his room and comfortable". I needed to buy some time.

I'd survived my first honey trap assignment, but the worst was yet to come: I had to tell Angie what had happened. I felt horrible, but she assured me that she was happy to know the truth after torturing herself for years. We both knew this wasn't a one-off.

That night, my inner spy slept well. I may not have saved the world from terrorism, but at least I had the satisfaction of imagining Tom calling the number I gave him and getting my cab firm instead.