I have just had an exceptionally delicious double macchiato in a stylish little antique shop/cafe called Costa's Barbers in Battersea High Street. Strong, rich, with just the right small amount of frothed milk. The cake(s? - I only saw one) looked good too. I think it's closed Sunday -Tuesday. On Saturday you can buy thin-based pizza from the van outside - mine was pesto, mushroom, chilli and goats cheese - and eat it in the cafe.
On the down side, the coffee in the generally excellent Breton-run Deli Boutique on St John's Hill is poor.