I work near Covent Garden in London, and one of my favourite beauty resources in this area is The Garden Pharmacy, in Long Acre.
It's a convenient shop if I'm looking for the main department store brands and don't want to venture onto Oxford Street. There are Chanel, Dior, Lancome, Estee Lauder, Clinque and Clarins counters, and they also stock Art Deco cosmetics. Art Deco eyeshadows are well worth a look - they're small, but they're only £5.50 each and very good quality.
They also stock comprehensive selections of La Roche-Posay and Avene, including the La Roche-Posay Anthelios sun care.
Other brands that can be found here include:
Ren, Cowshed, Nuxe, Darphin, Dr Lewinns, Dr Hauschka, Klorane, Phytologie, Korres and I Coloniali. I particularly like the I Coloniali Bamboo Bath and I Coloniali Body Massage Cream.
The website is at www.garden.co.uk. It's well worth a visit if you're in London.