Mortgage brokers and intermediary lenders in the UK are united in their concern that inflated house prices are the gravest threat to the success of the Help to Buy scheme.

According to the latest outlook report from the Intermediary Mortgage Lenders Association (IMLA) almost two thirds of intermediary lenders and brokers, 60% and 59% respectively, single out a house price bubble as the most likely factor that may undermine the government scheme.

The research shows lenders already anticipate a 2.7% increase in the average house price by the end of the year, pushing it to £166,418 according to the Land Registry measure. Lenders’ prediction is based on the market’s performance in the first half of 2013 and the initial impact of the Help to Buy equity loan scheme.

If this same growth rate continues for the duration of Help to Buy, the average house price will reach £180,265 by the end of 2016, an overall rise of 11% in four years. This would bring house prices close to their last peak of £181,975, which was recorded in November 2007. There are concerns that the rate of increase could be even greater with the upcoming Help to Buy mortgage guarantee offer still to launch in January 2014.

Brokers also register significant concerns about a potential lack of lender support for Help to Buy, with almost half, 48%, worried this will jeopardise the scheme.

Despite these concerns there is an agreement that first time buyers will see the greatest benefit from the upcoming Help to Buy mortgage guarantee with 100% of lenders and 89% of brokers taking this view.