I'm crushing on London illustrator/photographer Kat Heyes. Her watercolors are so charming, it's impossible to pick a favorite. And her photography is really wonderful too. (She did a lovely book with her sister-in-law called The Happy Campers. It brings back so many fond summer memories for me.)
Heyes, a girl from mid Wales, also has an impressive list of clients: Gucci, Vogue, Elle, Calvin Klein, Marie Claire. It's easy to understand why!