Buy to let has been described as the glue holding the current housing market together, with strong rental demand helping to avoid a painful housing crash.

In a decade that saw house prices triple in value, buy to let surged forward and attracted a range of investors. Since the market began in 1998, it has grown to represent 10 per cent of the total market.

Conversely, the housing market experienced a significant decline in the wake of the global credit crunch, and analysts tipped that it would fall a further 10 per cent this year.

Bradford & Bingley, the number two player in the buy-to-let sector through specialist arm Mortgage Express, said the fundamental drivers behind buy to let such as immigration, fewer people per household, a more mobile workforce, first-time buyers unable to get on the property ladder were driving rents higher.

Rising rental yields in turn meant landlords were able to pass on the impact of rising mortgage rates straight to tenants.

Jeremy Law, head of buy to let at Bradford & Bingley, said, "Buy to let is likely to remain double digits in terms of the size of the broader mortgage market. It's now well over 10 per cent and that is likely to continue.”

There was little doubt that buy to let borrowers, particularly newcomers, were facing a drought of new mortgage products but lenders said this was due to markets and not credit quality.

Andy McQueen, managing director of specialist lending at building society Nationwide, said, "The major factors slowing the buy to let market are confidence and mortgage supply. Many of the fundamentals of the business, however, are still strong."

According to price comparison site Moneysupermarket.com, the number of British mortgage products on offer had dropped to 4,025 last year to just 670. Almost 600 of them were removed since the end of March.