Do face masks work?

I went into the chemist's yesterday to buy plastic gloves but they had none. Instead they sold me masks and i wore one for the first time in Carrefour, but not in the street like most of the few passers-by.

Dr John Lee in the Spectator seems to think I might have been wasting my time even in the shop. He asks if a face mask protects you from the virus and answers his question

...don’t expect it to stop you getting the virus from aerosols – which are likely to have an important role in viral transmission, especially in crowded or busy environments.

Viruses, he thinks, are just too darned small.

He concludes:

So does wearing a mask protect others if you’re infectious? There’s little direct evidence to say that it does, and quite a lot of straightforward reasoning to suggest it doesn’t.