House prices in towns near the M25 are more than six times higher than when the motorway opened 30 years ago, having risen by over £900 a month.
The average house price in 40 towns near the M25 has grown from £59,183 in 1986 to £385,085 now. By comparison, the Retail Price Index has increased by 169% over the period.
The £325,903 increase in prices of these M25 towns has significantly exceeded the £208,163 rise in average house prices nationally, says the Halifax.
"House prices in towns close to the M25 have grown significantly since the official opening of the motorway in 1986," says Martin Ellis, housing economist at Halifax.
"In terms of average values, the most expensive towns close to the London Orbital are in the southern section of the motorway and on the north side, while towns east of London typically have the lowest prices."
Ten towns close to the M25 have seen prices rise by over £400,000 since 1986. Barnet in Hertfordshire has shown the biggest increase, with the average price growing eight-fold from £69,744 to £539,708.
The next largest rise has been in Rickmansworth, Hertfordshire, where the average value has grown by £468,448. It's now the most expensive town on the M25, with an average house price of £551,959.
Meanwhile, eight of the ten least expensive towns are on the eastern section of the M25 in Essex and north Kent, including South Ockendon, Grays and Erith.
However, despite the large price rises, average values for the M25 towns are now significantly below those for London as a whole - the opposite of the situation in 1986.
"Towns have, on average, outperformed the South East region as a whole with an average price £52,000 higher, yet prices have failed to keep pace with the dramatic rise in property values in the capital over the past three decades," says Ellis.
"As a result, towns around the M25 are now typically significantly lower than in London, despite being on a par when the motorway opened."
Top 10 M25 Towns House Price Growth since 1986
Barnet, Hertfordshire: 674%
Rickmansworth, Hertfordshire: 561%
Reigate, Surrey: 623%
Leatherhead, Surrey: 505%
St Albans, Hertfordshire: 647%
Chigwell, Essex: 605%
Epsom, Surrey: 585%
Sevenoaks, Kent: 475%
Epping, Essex: 590%
Windsor, Berkshire: 591%