Estate agency Knight Frank said prices in the prime central London market - from Kensington in the west to Canary Wharf in the east - rose by 0.4% during the month, the first increase since last August and the biggest since last May. Prices were 0.7% higher than a year earlier. An increase in sales activity has boosted buyer confidence, sparking a healthy number of transactions and an end to price falls, Knight Frank said.