M25 motorway
Increased house prices. Before the M25, areas just outside London were a mixture of small rural farms and commuter belt. Its arrival helped those commuters get on their way faster, pushing house prices in such areas higher. "We know from our research that house prices generally have gone up about 300% since the M25 opened in 1986," says Anthony Wardell from Knight Franks estate agents. On the western side of London, house prices have gone up nearer to 400%, he adds.