London for under £20

I am never quite sure what people mean when they drone on about how expensive London is. Of course, if you are trying to buy a flat-fronted Georgian town house in one of Islington's leafier squares, then, yes, it is unspeakably expensive.

But if you just want to enjoy a nice day out - a walk, perhaps, then a bit of culture followed by something to eat and drink - what's the problem? Use your brain a little and you should be able to do all of these things, and still have change from a £20 note.

It can be fun, doing London on the cheap, as a friend who has recently downsized pointed out to me only the other day. She had walked from her flat to my house to save herself a Tube fare and, on the way, had called in on the walled garden at the Geffrye Museum, a hidden jewel of the East End (admission free).

Visiting a park or a gallery costs nothing; neither does a little light window-shopping at Harvey Nichols or Selfridges (and if you really must spend, buy a fake rose for your hair or a cheap and cheerful spangly hairslide). The bus journey there, meanwhile, is only £1 a throw and is a treat in itself if you are sitting on the top deck of an old Routemaster.

On Sundays, I like to visit the Columbia Road flower market. If you strike at the right moment, you can buy a whole tray full of bedding plants for a fiver. Breakfast - a latte and a croissant from a van or, if I am feeling strong of stomach, some seafood from a nearby stall - sets me back less than £4. From here, you can walk to Spitalfields via Brick Lane.

It's busy and vibrant and there are lots of groovy bargains to be had. As for supper (my friends from out of town are always grimacing and rolling their eyes at London restaurant prices), even that is not a problem.

I am mad for the scallops with asparagus and garlic at the award-winning Busaba Eathai in Soho, and you can have a bowl of these and a glass of wine, people-watch for an hour or so, and still need only to hand over a couple of coins with a £10 note.

In fact, when I think about it, even if I were a millionaire, there would still be times when only those scallops - yours for just £8.80 - would hit the right spot.