Half of the houses on sale in Harrow have been on the market for more than three months, according to a new survey.
In January only 20 per cent of properties in the borough were on the market for more than three months, but this has near-tripled to 56 per cent last month.
Estate agents have experienced setbacks as buyers who have found properties have had their mortgage offers withdrawn by lenders.
Often prospective buyers have difficulties finding a mortgage, delaying their search for a home.
Across London 51.2 per cent of properties were unsold after 90 days according to a survey by Globrix, a property website.
Lee Pottle, a partner at Elliot Lee Estate Agents, said: "Applicants can't borrow the money, unless lenders start offering better prices I can't see it changing.
"Houses that are selling are properties that need work and ones that have come down in price in the last six months."
Mr Pottle added that the firm had seen an increase in renting.
Gary Rawlinson, a partner at Rawlinson Gold, in Harrow, said: "It is a nationwide issue.
"People can't get mortgages and psychologically some people are holding back from purchasing because they think it is not the right time."
He added the government decision to axe stamp duty on properties under £175,000 for a year will have little affect on the affluent suburbs of Harrow.
The average price of a property in Harrow was £302,262 in July.
He said: "There are not that many properties in this area for £175,000, the Government needed to go up to £250,000 as that is when stamp duty goes up to three per cent.
"The public think they are doing something, but the government are doing the least they can and getting away with it."
Barry Macleod-Cullinane (Conservative), portfolio holder for housing, believes residents need to start being more economic.
He said: "Lenders are taking a lot of products off the market and it is difficult to get a mort-gage.
"It is difficult to start up home - if I was a buyer I wouldn't be rushing in.
"Harrow Council is looking at what it can do but I would advise residents to go to the citizens advice bureau and check their finances."