A rental market index collated by property portal Rightmove found demand was at its highest ever level.

Asking rents outside of London are also growing faster than those inside the capital, its research found.

Rental prices rose 2.7% on properties outside of London in the last quarter, compared to 2% within the city’s boundaries.

The fastest rate of growth outside of the capital was Bushey in Hertfordshire where prices grew 21%. The next biggest rise was in the Kent town of Deal which saw prices leap 13%.

Inside London it was Battersea which led the pack, with rents growing 14%.  The areas of Wembley and Brondesbury were second and third in the rankings, both up by 11%.

The North East was the only region in England where rents fell, declining 0.5%. Wales suffered a larger fall with rents down 2.9%.

Sam Mitchell, head of lettings at Rightmove, said competition in the rental market continued to be fierce but warned that affordability was becoming a big issue for many renters.

“Rents have grown this quarter in nearly all regions of England and Wales, fuelled by demand outstripping supply in many of the sought after areas, especially in the East of England and the more affordable areas of London,” he said.

“The smaller rise in the capital is likely to do with the fact that costs in many areas are nearing many people’s affordability ceiling.

“Tenants staying longer in a property is contributing to the lack of supply in some areas, and agents tell us that in the most in-demand areas good properties on at the right price are being snapped up within a few days.”