I'm in London and have to report there is very little in the way of kilt shops, there is one opposite the British Museum, but to be honest it's not up to much, and they only have a small shop with lots of scarves and the like and they are geared more to the souvenir market, they have a second shop on Porotbello Road as well, but I was in it a few months ago, and there wasn't a kilt to be seen, and although the shop was empty , I wasn't even greeted by the assitant who was too busy reading a magazine... I'll have a think of other places as well and let you know