I can make a recommendation...... my wife.
Viola is a qualified & trained designer who specialises in bespoke evening and special occasion wear etc. She also undertakes alterations, all in the privacy of her studio, so no need to take off/try on clothes whilst standing in a drycleaners.
Based just off Battersea Rise (Between the Commons).
Have a look at
http://www.violarntzen.co.uk/ for more info or call 07813 118 707 to make an appointment.