According to new research 63% of homeowners aged 55 and over in London are likely to downsize their home in the next five years.

The research has quantified the size of the UK’s "Last Time Buyer" (LTB) market, which is worth £820billion and is forecast to reach £1.2trillion by 2020.

It found there were 5.3million under-occupied homes in the UK, with 3.3million LTBs looking to downsize.

I put the figure of unused bedrooms in these properties at 7.7million.

The study found the main reason given for not having downsized already was houses being small enough and occupants unwilling to give up their family homes.

Legal & General CEO Nigel Wilson said: “The LTBs are an overlooked part of the housing market, yet they could play a significant part in solving the UK housing crisis.

“Helping young people to get onto the housing ladder through initiatives like Help to Buy is important, but enabling older people to realise their downsizing dreams could have a far greater impact in terms of unlocking family housing stock for people to buy.

“To unlock the potential of the LTB market, we need to build more of the right type of housing – two-bedroom properties suitable for older people and near family, friends and facilities.

We also need the right tax regime to incentivise moving, with Stamp Duty a key focus and better options to allow for equity release so if older people want to stay put by accessing their housing wealth they can.

"If we get those right, we can help older people in the UK move to properties which better fit their lifestyles and their needs, and, in doing so, free up larger properties suitable for growing families.”