The common-sense economic case for these currencies was summed up for me by John Walker, acting treasurer of Brixton LETS in London: "They're more appropriate for local communities, because the money doesn't drain out of the local community."

That seems plausible: The money (Brixton bricks) goes 'round and 'round Brixton and isn't sucked away by the insidious multinationals of neighboring Clapham. But this is one of those cases in which common sense lets us down. Money, whether pounds or Brixton bricks, isn't wealth. It's just a way of keeping accounts, and swapping one system of accounts for another isn't going to alter the basic productive potential of Brixton.