A slump in super-prime home values in London is rippling down the luxury-property market.

Sales values per square foot for houses priced between 2 million pounds ($2.6 million) and 5 million pounds fell by 8.4 per cent in the second quarter from a year earlier as political uncertainly deterred potential buyers, according to data compiled by researcher Lonres. Selling prices for super-prime properties — those over 5 million pounds — fell 3.2 per cent.

“The very top end fell first and hardest on higher stamp-duty charges and the Brexit vote,” Marcus Dixon, head of research and data analysis, said in a telephone interview. “Now, with further political uncertainty, we are starting to see falls filter down into prime central London.”