This is my first post on this forum!
I live in London as well (not many of us about on this forum), where did you get your HC from?
I live north of the river and tend to go to Crewes Hill in Middlesex (if you know it), Home Marine, Wildwoods etc. Never seen HC for sale there though.
I'm also trying to get hold of some Blyxa, which seems to be impossibe here!