Average house prices in London have jumped 19% in a year, with the typical cost of a property in one borough set to pass the £2m mark for the first time within weeks, according to new data.

The report, issued by estate agency group LSL Property Services and research firm Acadata, stated that, following a "temporary waning" of growth in the capital's market, the average London house saw 2% – or almost £11,000 – added to its value in June alone.

In Lambeth the annual rate of price growth is running at 38.5%, while Wandsworth and Waltham Forest each notched up 25%-plus. Meanwhile, the average price-tag in Kensington and Chelsea – dubbed by some "the richest borough in Europe" – has climbed to £1.99m and "looks poised to set an average property price of £2m within the next few weeks".

The report said the average price paid for a house in England and Wales now stood at £270,636 – up 9.9% on a year earlier. But David Newnes, director of Reeds Rains and Your Move estate agents, owned by LSL, said the government's policies on housing "should not be led astray" by what was happening in prime central London.

He added: "If London and the south-east are removed from the equation, the annual change in average houses prices drops to 4.6% ... Outside of London, the south-east and east Midlands, prices dropped and stabilised across all other seven regions in June." Newnes said further interventions or tighter rules "could fracture the health of the recovery".

Brighton and Hove and the Dorset town of Poole were among the locations that notched up annual growth of 19-20%. In Poole the average price of a detached property has jumped by £60,000 over the year. Meanwhile, areas where the annual growth figure exceeded 10% included Bristol, Bournemouth, Luton, Rutland, Slough and Worcestershire. By contrast, Cornwall saw prices fall by 1.8% over the year. The area that was said to have seen the largest fall in annual prices was Merthyr Tydfil, down 7.3%.

The report also stated that overall, 90,000 properties were sold across England and Wales in July – up 21% on a year earlier, and the highest monthly total since November 2007.