Residential property transactions fell by 4% between June and July, according to new figures from HM Revenue & Customs.
July's seasonally-adjusted figures were just 0.2% higher than in July 2014.
In total there were 100,720 residential and 10,100 non-residential transactions last month.
Jeremy Duncombe, director, Legal & General Mortgage Club, said the figures were in stark contrast to last week's figures showing the best July for seven years.
He said one reason that lending and transaction figures are not increasing at the same rate is due to a lack of properties pushing up house prices.
“If only a few properties are available, those who are looking to buy will have to bid against each other to try to secure the property.
“A higher sale price will mean the buyer has to apply for a larger mortgage, which means lending figures increase faster than transaction numbers.”
Peter Rollings, chief executive of Marsh & Parsons, said that sales in July may have slipped back slightly month-on-month, but the market was “working overtime” in June to regain ground lost before the election.
“Ever since the stamp duty system switch-over, property taxation has become more of a sticking point in London, and here buyer demand has slowed somewhat at the top-end.
“It will take a while for these changes to fully bed in, and in the meantime house price rises and property sales in the capital may be outshone by other UK regions for the months to come.
“But that’s not to say they’ve fallen out of line – and with an average 12 buyers chasing every available property on the market, the strength of the demand for homes in London will continue to push growth up a gear.”
Doug Crawford, chief executive of myhomemove, said the big question now is the timing of an interest rate rise from the Bank of England.
“Many would-be buyers are keen to purchase while mortgage rates are so low. Increased anticipation of rate rises is putting greater pressure on buyers and competition for homes for sale could drive up prices further in the short term.”