Defaqto has found that average margins, above the Bank of England base-rate, charged by base-rate tracker mortgages have risen sharply since the lowest margins were applied back in autumn 2007 – when a two year base-rate tracker was available at 1.01% below the base-rate for a mortgage up to 90% loan to value.

At the same time, however, since their peak, which occurred between September 2009 and February 2010, average rates for base-rate tracker mortgages have fallen.

David Black, Defaqto’s insight analyst for banking, said: “With the base-rate having remained at a half percent since for well over two years