Andrews & Robertson posted sales of £16.7m, with a 73% success rate, from the 68 lots offered at its latest auction.
The figure was significantly more than the £10.8m raised by A&R last month and the £10m it posted last July.
However, the success rate was down on the 83.4% achieved by the auction house over the first six months of 2016.
The largest lot was a recently refurbished six-bedroom Victorian house in Queens Park, NW6.
Guided at £2.8m, the freehold property was offered with full vacant possession and sold prior to the auction for £2.8m.
A freehold cleared site in Brixton, SW2, with planning permission for four homes, exceeded its £1.3m guide price, selling under the hammer for £1.5m.
Chairman Robin Cripp said: “This was our first auction post-referendum, and the results show that there is still strong buyer demand across all sectors, despite the uncertainties surrounding Brexit.”
The sale took place at the Montcalm Hotel, W1, on 21 July.
