I'm wary of reviewing this as I want to keep it all to myself! But as it was originally recommended to me by my friend, I thought I'd share the love.
I go to Rozi for my eyebrow threading and sometimes my upper lip too. She has revolutionised my eyebrow shape! I admired my friends as hers were so sharp and defined, and I thought mine could never be like that, but Rozi has worked wonders! If you don't want them so 'done', you may have to ask, but I love the clean, smooth lines that she creates.
Before this I used to go the Vaishaly Patel in Maryelbone as it's close to my house and lovely. Rozi's may not be as chic, but it's less than a quarter of the price, and when it comes down to it they both do a really good job.
When I go away on business and can't get my eyebrows done for a month or two, I try to do them myself, but I always end up running back to Rozi begging her to restore them. How do they make them so defined? What a skill. Much to recommend.