Dragonfly had £337m AIPs at start of 2012

The spike in AIPs, from an already high level, is yet more proof that professional property investors and landlords remain extremely active within the increasingly flat residential property market.

With property prices under continued pressure and many prospective homeowners unable or unwilling to purchase property, Buy-to-let was the single biggest driver of the surge in AIPs.

Mark Posniak, marketing and operations director at the lender, said: "With residential property prices falling and high street mortgage criteria tightening quite dramatically, it's no surprise investor demand is rising by the day.

“It's been well documented that buy-to-let is booming and these numbers drive home how big the sector has become. It's not something limited to London, either.

“The AIPs are coming from all areas of the country and are on loans of all sizes. Both amateur and professional investors see a major opportunity in the market at present and they are becoming even more active as the market falls.

“Their view is that the owner-occupier market could be flat for years to come."