Rightmove says rents across England and Wales, outside London, are up 1.3 per cent in the past three months according to what the portal calls "the largest rental property data set" of any index.
In Greater London, by contrast, Rightmove claims the affordability ceiling looks to have been reached with rents up only 0.2 per cent in the past quarter.
The portal's regional breakdown says the annual rental growth in the East of England is the highest in the UK, up 6.4 per cent in just one quarter. Individual locations within the East of England dominate a 'top 10' investment list drawn up by Rightmove, headed by locations in Essex and Hertfordshire.
"Those landlords who bought in the East of England are seeing much higher returns on investment as the region leads the way for rental growth. But with a combination of such high returns for buy-to-let landlords and affordable prices for first-time buyers, demand for property is high and results in a stock shortage problem" according to Sam Mitchell, head of lettings at Rightmove.
He warns the government not to allow its proposed reduction of claimable allowances for landlords not to backfire, which may indirectly result in landlords exiting the sector and leading to a further shortage of stock - and increasing rents.