I'm going to want stars for rooting through my purse for you! (Just thought I'd tell you in advance...) I use a place called Glow Beauty Bar which is one of the department stores on Oxford Circus (I can't remember which one but there's a row of them) for my eyebrow threading and dying (I swim a lot) and I'm relatively sure they do extensions in there. They're also very good and the staff are lovely.