Londoners are buying more homes outside the capital as prices remain too high, even after the end of a decade-long housing boom.

In the first half, Londoners bought more than 30,000 homes outside the city, a 16 percent rise from a year ago and 61 percent more than in the same period a decade earlier, according to research by Hamptons International. Nearly 40 percent of leavers relocated to the south east of England, followed by 30 percent who moved to the east of the country.

"With affordability stretched, more Londoners are moving out of the capital to find their new home," said Aneisha Beveridge, a research analyst at Hamptons. "More people are making a bigger move and buying a larger home sooner to avoid having to pay stamp duty on additional moves as they trade up."

Despite a recent cooling in the market, home prices in the capital have still almost doubled in the past decade after demand outstripped supply and low interest rates fueled purchases. The surge in home values, which now cost the average Londoner a record 14.5 times their annual salary, mean that many city dwellers can no longer afford to buy.

Stamp duty on a home worth £483,800 ($621,500), the London average, is £9,190 for first-time buyers and £14,190 for those who have previously owned a property, according to the U.K. government's website.