My dad did a McCartney too

I first met my dad's new girlfriend over lunch at a Chinese restaurant in Queensway. Her name was Jade, she was a model, and she was only 20 years old - seven years younger than me. I can't remember much about the lunch because I was probably in shock.

It does stick in my mind, though, that she had long blonde hair, and was wearing a short skirt and high heels. The waiters must have thought she was my slightly trashier younger sister.

I was incredibly embarrassed. It was one of those cringing-at-your-parents moments and I kept thinking to myself, "Oh Dad, get over it". Jade was very sweet and polite but I could tell she was a bit scared of me. We didn't know what to talk about and my dad had to keep making small talk. I'd known he had a girlfriend, and that she was younger than him, but I hadn't realised exactly how young until that day.

That was four years ago. My dad, Dario, is now approaching his 60th birthday, and he and Jade got married last year. They now have a little boy, Dylan, who has just turned one. I still find it odd that my daughter Lola is nearly two years older than my halfbrother.

I grew up in Kingston, Surrey, with my younger sister, Star, and we had a really happy childhood. My parents separated amicably when I was 14 and my mum hasn't remarried. For years I had an image of the ideal stepmother in my head. Dad used to play tennis and there were lots of women at his club whom I thought would be perfect - fit, attractive women his age. He had a few girlfriends over the years when he was single, but nothing serious.

I did wonder at first what Jade saw in a man more than 30 years her senior - I doubted they had anything in common, but you can find happiness and love at any age. I have never been attracted to older men, but my dad is charming and handsome so I've always been aware that women liked him. When he used to pick me up from school, the female teachers would always come over and say hello.

I have never tried to sabotage their relationship. When they first started going out I don't think anyone thought it would last.

At the back of my mind I was thinking, "Yes, this is a ridiculous situation but I want my dad to be happy". He tried to sit me down and talk about it but I felt awkward - I suppose I was worried about saying something that I would later regret. I didn't tell him what I really thought because that would have been cruel.

But as the months went on, any chance of talking dad out of it passed. Jade obviously wanted me and my sister to like her - she knew how close we are to dad, and how much he values our opinions. It was hard for her to be introduced to her boyfriend's grown-up children and we did feel a bit sorry for her.

Ever since Paul McCartney started seeing Heather Mills he has started dyeing his hair and wearing younger clothes - at least that hasn't happened to my dad. He's retired now but he used to work in fashion, so he's always been a bit of a quirky dresser. There are some little things I have picked up on - he has started listening to Madonna and going to the gym - but he hasn't changed too much.

When dad told me that they were getting married, I wasn't that shocked - by that point I had accepted their relationship. It was a register office wedding and when I signed the form as a witness I thought, "This is really surreal".

Mum was invited to the wedding but she declined; she would have felt uncomfortable. She is a down-to-earth Scot and has been brilliant about it. Most women wouldn't be able to swallow the fact that their ex-husband remarried a much younger woman, even if they had been divorced for a long time, but she's taken it well. If anything, she thinks it's amusing - sometimes she just laughs about it. My mum and stepmother aren't friends but there's no bad feeling between them. When I found out that Jade was pregnant I thought, well, she's a young woman and of course she wants a family. I went through a mixture of emotions. I was happy for them, but I felt a bit resentful that my dad was starting a whole new family. But Jade's pregnancy actually helped us bond because I had been through the whole thing with my daughter.

As I got to know her, I dropped my reservations about her. We don't have a lot in common other than our ages, but she's sweet and kind.

My relationship with my dad has changed quite a lot - even though I am an otherwise mature thirtysomething, I can't help feeling resentful that he is not just my dad any more. I don't see that much of him now, and when I do he's always tired. When I was a child, mum was very hands-on, while dad was always at work.

I know how hard it is to have a toddler and I wondered how he would cope. When you have a baby you expect your parents to help with baby-sitting, but that's shifted because I'll be the one baby-sitting for him. All sorts of silly things keep popping into my mind.

Things like, if for some reason I lost everything and have to move back in with him, I would feel I can't because it's not really my home any more as he's got a new family. But I have my own family now. I am sure once Stella McCartney starts her own family, she'll feel the same way. I think my sister, who is the same age as Jade, has found the situation harder to accept than I have. After all, she is no longer the baby of the family.

Now that dad has a new baby, it would be churlish not to be positive about the situation - it's not Dylan's fault, after all. It's not conventional and I'm sure people stare at them in the street.

I sympathise with Stella and her brother and sisters, because they have to deal with family problems in the spotlight. With step-families, it's never a smooth ride and inevitably there are going to be issues to resolve. But after all, Jade will always be in my life and she has given me the brother I never had.