The value of urban development land outside of London has fallen by a third in the past year, according to research by property consultant Knight Frank.

The Yorkshire and Humberside region has been most affected by the downturn, with brownfield sites in the worth now half of their value in September 2007. North-west England followed closely behind, with a 41% fall in land value.

London has resisted the worst effects, with inner-city prices falling by 0%, whereas areas in outer London have fallen 15%.

Knight Frank said the increasing presence in the market of housing associations and speculators will help to prevent a repeat of such sharp falls in land value over the next year.