The largest national letting agency, Countrywide, says the market is now so buoyant that a third of landlords are able to re-let their property before the existing tenant moves out.

So far in 2015, it says that 33 per cent of all new lets were agreed while the property was still occupied, up from 27 per cent last year. 

The average let agreed while tenants are in place is equal to 105 per cent of the asking rent, or an average of £35 a month more than the asking rent. 

With landlords still receiving rent from the vacating tenant, they are under less pressure to negotiate. In comparison tenants moving into an empty property have more room to negotiate on the rent, knocking an average of £21 a month off the landlord’s asking price. 

In London, 51 per cent of new lets are agreed while there is still a sitting tenant in the property, up from 41 per cent in 2014. 

The level of demand from tenants in markets where the level of demand is highest and the time to find a tenant is shortest, means landlords are able to reduce the time a home is empty, Countrywide suggests.

Where a deal is agreed before the existing tenant leaves the property, there is an average of just six days between the existing tenant moving out and a new one moving in. Some 10 per cent of the time a new tenant moves in on the same day that the existing tenant moves out.

“In larger rental markets, more new lets are being agreed well in advance of the current tenant leaving. As a result we’ve seen void periods fall, with a growing number of landlords having a new tenant lined up over a month before their existing tenant leaves. While leaving some time for maintenance between tenancies is advisable, increasingly there’s just a matter of hours between a tenant moving out and one moving in” says Countrywide research analyst David Fell.