According to Mr Morrey, this has created a "captive market" where lenders can levy a higher rate on five-year fixes and still sell the product as for some landlords it is the only option.
Mr Morrey added that the drop in costs for buy-to-let lending in general was not unexpected given the high level of competition in the area and the fact the market had seen some signs of declining demand due to changes to tax and regulation.
He said: "To grow or even maintain market share, lenders are shaving down their rates as much as they can and looking to tweak their criteria to cast a slightly wider net."
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