So-called ‘mortgage prisoners in the capital face £9,364 in annual interest payments, 37% of the average disposable income in the capital, according to analysis from online mortgage broker Trussle.

This level of interest would cover a full deposit for a UK property within three years. It is also more than triple the £3,025 paid by a mortgage prisoner in the northeast, where the annual interest payments equate to 18.7% of disposable income.

Trussle says those’ in London stuck of their SVR could be losing close to double the proportion of their post-tax income on excess interest each year compared to those in the northeast.

The disparity is the result of the major difference in outstanding loan value between mortgage borrowers from each region. In London, the average borrower has more than £243,200 left to pay on their mortgage, compared to £78,600 in the northeast. Other regions where mortgage prisoners will be hit the hardest include the East and Southeast of the UK.

Ishaan Malhi, CEO and founder of Trussle, said: “Many factors are contributing to the troubling number of mortgage prisoners across the UK, and we’re now seeing that geographic location also plays a large factor in how hard you’ll be hit should you end up stuck on your lender’s SVR. For borrowers based in London, the southeast, and east of the UK, the annual interest payments can be absolutely crippling.

“While some lenders do offer help to mortgage prisoners, too many are in effect holding these borrowers to ransom, while they collectively lose around £13 million per day in excess interest. This needs to change urgently. Our recent Mortgage Switch Guarantee proposals call for a new set of industry standards to be implemented to help borrowers on SVRs switch mortgage. One of the key proposals recommends that all lenders have some form of duty-of-care to their customers, possibly in the shape of offering a range of relief options to mortgage prisoners.

“Whether this takes the shape of a payment holiday when it’s clear a borrower can’t afford their payments, or an obligation for lenders to refinance mortgage prisoners who meet certain criteria, it’s clear that addressing this issue is more urgent than ever.”