Luke Blackall: I'm all for pies, pop-ups and "squatter" restaurants

I hate to see empty buildings in the centre of London. It's not just the houses, flats and apartments that could house entire communities, but also those places that could provide exciting bars, restaurants and galleries for that community.

So many are bought as investments, which ramps the price up, and drives people outwards. So I was pleased to go to town this week for the launch of Pret a Diner, which has taken over an enormous – and empty – former casino on St James's Street.

The people behind the venture have turned the five-storey townhouse into an art gallery and Italian restaurant (albeit with a French name), which will run until the Olympics. It was also nice to have it described as that most awful of phrases, a "pop-up".

The place was packed with the polished patrons of the party scene. And with half of them crowding the kitchen, waiting for more food to come out, and the other half hanging around on the stairs in the half-decorated hallway, it felt (in a good way) like the venue was squatting there.

The following night, I went to the Seagrass restaurant in North London, a place that actually describes itself as a "squatter restaurant". It isn't there during the day, but in the evening, it comes into its own.

During daylight hours, it is M. Manze, one of London's dying breed of traditional pie and mash shops. The place used to close in the afternoon, but recently a man who lives in the flat above (who happens to own a meat and seafood supply company), decided to run a restaurant there in the evenings.

He couldn't have chosen a better spot. With its white tiles, mosaic floor, wooden benches and hanging lights, it has the type of retro look that owners today spend millions trying to achieve – except for the fact that it is all original.

The food was fresh, simple and remarkable, given that they use a kitchen more set up for baking pies than fine cuisine. But one of The Seagrass's triumphs is the way it uses space. With a huge percentage of new restaurants failing, and prices and rents being constantly driven up, paying to squat in someone else's restaurant when they're not using it seems like a sensible and cautious approach to take. It is one trend that I hope catches on.