Vintage shops in London

Anyone here know a few shops (antique,thrift, clothing and etc) in London that could sell vintage hats like bowlers, toppers and boaters?

There's been another thread like this recently, but I can't remember the title. Edward will probably be more helpful, he lives in a London district that is a great place for vintage.
The best place for hats is Christys, but they do have a hefty price tag. Look up london's famous street markets if it's a bargain that you are looking for.

I am looking for vintage hats but willing to stop by Lock & Co in Central London next year for a boater for myself, panama and fedora for my parents.