That’s me in the picture: Cherie Blair, the morning after Labour’s election victory, 2 May 1997

We had got home at around 6.30am, after Tony made his speech about the sun rising on a new Britain, and I was trying to catch up on my sleep. The doorbell rang at around 8 or 9am, and I could hear the policeman and delivery man talking: our bedroom was at the front, so it was as if they were in the room. The policeman called up and I asked if they could leave the flowers on the porch. He said no and I thought, perhaps they’re worried about bombs. So I opened the door.

It was such a terrible mistake. There was a great flash of bulbs, though they only got four shots because I shut the door pretty quickly. The photographer who took this, Mathieu Polak, was jolly lucky: the chap from the Telegraph was changing his lens and missed it. It’s been reported that a tabloid sent the flowers, to catch me out, but they were sent by the children’s primary school. It was so kind of them.

We had barely drunk anything the night before. It was all quite tense, really – waiting all day, and when the message came that we were ahead, there was no time for drinking.

I was very upset when the press said I was wearing some sort of nylon thing: it was a high-quality, cotton nightie from Next and I bought it especially for the campaign. We were travelling around the country and there were always people coming in and out of our bedroom. It was a lot better than you might expect from a mother of three.

I didn’t tell Tony about the picture. He was very busy doing important things, so he didn’t see it till it was in all the Sunday papers. My hairdresser, Andre Suard, came and did my hair later that morning, then Tony and I drove to see the Queen, and our neighbours lined the streets; we drove through London with a helicopter overhead and people flashing their headlights.

This photograph was the moment when reality set in. Until then, we had talked to the Home Office about staying at our house in Islington – but with the press parked outside, disrupting all our neighbours, it just wasn’t feasible.

We moved into Downing Street that weekend. We were the first couple in a very long time with children, who were 13, 11 and nine, and Number 10 wasn’t big enough; so we moved into the chancellor of the exchequer’s flat, Ken Clarke’s. The children were very excited. There was a big old wardrobe in Kathryn’s room, like the one from The Lion, The Witch And The Wardrobe, and she got into it with her friends; it fell over and had to go. We hadn’t booked a removal man, so we moved all the clothes and toys ourselves, and there were photos of that, too.

I look back at this picture and feel mortified, but everybody else thought it was very human. I always had a good relationship with the photographers: they’d send me nice pictures, with a note to say it wasn’t the one their picture editor had chosen. Do I have any advice for someone new to No 10? Never open the door in your nightie. And that everybody has to adjust to it in a way that’s right for their family.

My abiding memory of those two days was the sheer euphoria, the sun coming up as we drove down from Tony’s constituency in Sedgefield, him going quiet and feeling very responsible about what should happen next. My home seat, Crosby, went Labour for the first time in my life.

Life was never going to be the same again. I’m incredibly proud of that night, and I think we did change the country for the better.