Landlords bought 12.5% of homes sold in Great Britain last year, down from 14.7% in 2016 and 16.3% in 2015 – with the proportion of homes sold to landlords falling in every region.

The falling number of landlord purchases has meant the number of homes in the rental market has dropped.

In December 2017 there were 4% fewer homes to rent across Great Britain than in December 2016, with London recording a 21% fall, the largest of any region, according to the Countrywide Lettings Index.

London was also the worst affected for sales, with 5,400 fewer homes in the capital bought by landlords.

The index also found that last year rents rose by an average of 2.4%, an increase from 1.8% in 2016 – however this was still behind 2015 and 2014 which saw 3.2% and 4.9% increases respectively.

The average rent ended the year at £960 per month, up by £23 from the start of the year, with 46% of landlords increasing the rent when re-letting their home, up from 37% in 2016.

In a reversal of 2016 when London had the slowest rate of rental growth in England, last year it had the fastest – rising 3.2% compared to the 0.8% fall in 2016.

Scotland, up 3.3%, was the only region where rental growth outstripped the capital.

Countrywide research director, Johnny Morris, noted most of the rise came from London, while the north of England saw rents rise at a slower rate than they did in 2016.

“Rental growth has been supported by a fall in the number of homes on the rental market, with the biggest fall in London,” he said.

“It looks like increased competition between tenants for rental homes will drive faster rental growth in 2018,” he added.