Now he says, after the Zombies have been and gone! I'll probably have a look there, since kites are cool anyway, so it won't do any harm! It's not on my actual route, but it wouldn't be terribly difficult to divert that way for a change, and it would only add a bit onto the distance. I know Garratt Lane since I used to live in Wandsworth, although I never noticed the shop, which isn't saying much, since I seem to be able to miss any number of interesting and useful things which I cycle past!
The Bob has a suitable tube for flags already welded into the structure, so attaching them is easy.