Housing worth £123 billion is barely used in Britain, researchers have calculated, and have called for a one per cent tax on second homes to dissuade people from keeping hold of mothballed property.

A new study by University College London (UCL) concluded that building new homes is not the answer to Britain’s housing crisis as they are likely to be bought up as second homes or investments in the most popular areas.

Researchers collected information from around one third of local authorities in Britain covering 40 per cent of the population and found nearly 340,000 homes that were rarely used.

The majority were in London and the South West and Kensington was found to be the worst, with £21 billion of underused property in the borough.

Around four in 10 people currently live in an area where the average value of barely-used homes is higher than those that are permanently occupied, suggesting that the most desirable properties are being bought for purposes other than use as a home, for example as investment opportunities or holiday homes.

Researcher Jonathan Bourne at University College London, said: “Some of the most surprising findings were the sheer value and quantity of low-use properties in some areas.