According to property website Primelocation.com’s September index, the top 25% of all properties by value is now worth £453,879, down £6,855 on last September.
However, there are large regional variations.
The top end of the Welsh market saw the biggest falls in that time, with the average prime property losing 5.8% of its value, followed by Yorkshire and Humber, down 4.8%.
Prices in London, which has the highest concentration of prime properties, fell by 1.2%.
Asking prices for the top 10% of properties by value in the capital fell by far more, dropping 2.8% between August and September alone.
Meanwhile, asking prices for prime properties in Scotland have increased by 2.2% over the past year, while small rises were also recorded in the North West, North East and South East.
Andrew Smith, research director, Primelocation.com said: “This fall in prices at the top end of the market is particularly interesting because the availability of prime stock has also decreased slightly. Usually we would expect fewer houses for sale drive prices higher but at the moment they’re actually falling.
“With the rise in the value of sterling, there could be fewer high net worth individuals looking to buy property in the UK from abroad. In addition, the higher income tax level and general economic climate seems to be prompting some wealthier homebuyers to leave the UK and live in countries with more favourable tax regimes and better opportunities.
“Taken together these factors are contributing to falling prices for properties at the higher end of the market.”
