Gemma tries it on: A night at Number 10

It's not every day a letter arrives with 10 Downing Street stamped across the envelope, but just before Christmas that day came.

David Cameron was inviting little old me round to his for a drink to toast the London Collections: Men. This was the most exciting invite I had received all year. Would I get to have a good snoop around? Would I get to steal an ashtray? Would I get to meet the cat?

Dress code: lounge suit. Now this was tricky: easy enough for a gentleman, but what does that mean for a lady? It was a menswear event where, odds on, the male-to-female ratio would be high, so I didn't want to stand out in a dress, yet at the same time I didn't want to go full on Le Smoking; too matchy-matchy, what with the menswear theme and a roomful of suits. There is also the small matter of not owning an Yves Saint Laurent two-piece, and if you are going to do it, then do it right.

I sifted through my wardrobe and came across my fail-safe outfit – a Reiss jumpsuit. It's short-sleeved, wraps over with a lapel and has peg-style trousers. It has seen better days but a quick pin-up of the hem and it was just about passable. It is definitely time, though, to start looking for a replacement in case the White House ever needs me at short notice.

Maje have done great all-in-ones for the past couple of seasons, and I've got my eye on one with a mesh panel at the front. Simple but chic. As black and white is a trend for spring, I found this one from IRO, it has long sleeves with a dropped, belted waist. But there is the risk I could look like a Bee Gee, and it is probably not a sensible choice for a red-wine drinker.

Last Monday, I arranged to meet my fellow editors outside the "plebgate" gates: there's safety in numbers. After we'd been IDed, scanned and had handed in our phones we headed up the stairs. These were not just any stairs, mind, these were the stairs Hugh Grant danced down in Love Actually!

A glass of red and more canapés than was probably polite later, I was blending in nicely in my safety-pinned outfit when Mr Cameron made his appearance and was guided around the room to talk to all the important people. Not me, obviously.

He stood on the platform to do his funny little speech and told us he was wearing Marks and Sparks pants. How embarrassing – so was I. I hate it when that happens.