In contrast, just one in 10 new homes in London were sold courtesy of the scheme.
For the whole of the UK one in five private dwellings built since April 2013 were sold through the scheme, yet in more depressed housing market areas the ratio is as high as 50%.
Grenville Turner, chief executive of Countrywide, said: “Claims that the Help to Buy Scheme is causing a housing bubble are far from the truth and the facts speak for themselves.
“As a proportion of transactions both parts of Help to Buy together support only 2% of transactions in London compared with 10% in the North West, where support is most needed.
In the first 10 months of the Help to Buy Equity Loan scheme being introduced 14,823 new properties were purchased, the majority by first-time buyers, while a further 4,666 new homes have been reserved.
House builders in areas of the North East in particular, where house prices remain well below 2007 levels, have relied heavily on the Help to Buy Equity Loan scheme to sell houses, with nearly half of new private homes built in the past nine months having been sold using an equity loan.
Turner added: “The scheme has had a positive impact on house builder confidence with many now believing that they can sell what they build, which as we know means they will build more.
“The extending of the equity loan guarantee allows developers to plan with some certainty that demand will continue to exist in 12 months’ time and goes some way to bridging the increasing gap between new supply and demand for property in the UK.”