Backbench pressure certain to grow after Liberal Democrats sweep to victory in Chesham and Amersham with huge 25% swing

HS2 and the government’s proposed planning reforms have been blamed for last night’s shock by-election defeat for the Conservatives in one of their heartland seats.

Sarah Green, the Liberal Democrats candidate, overturned a Tory majority of 16,000 in Buckinghamshire’s Chesham and Amersham constituency with a huge 25% swing, the 14th biggest ever seen in a by-election. The seat, which has been held by Conservatives since its creation in 1974, was contested after the death of former incumbent Cheryl Gillan in April.

Sarah Green

Sarah Green overturned a majority of 16,000 in the Chesham and Amersham seat in Buckinghamshire

Its loss to the Conservatives will heighten fears within government that proposed reforms to the planning system, which could see locals lose control over planning processes, could lead to more shock results in by-elections and at the next general election.

Works for HS2, which passes through a pair of 16km tunnels beneath the constituency, have also caused disruption in the area and raised concerns that local water supplies could be contaminated by tunnelling works.

In her victory speech, Green said that the Conservatives had “taken people across the country for granted for far too long”.

Lib Dem leader Ed Davey said the result would “send shockwaves through British politics”, adding that voters across the South of England “feel they are being ignored by the Conservatives, taken for granted on a whole range of issues”.

Davey added: “Above all here, actually, was the proposed planning reforms which will give so much power to developers and take away from communities and not result in the affordable housing people need. 

“But I think that was symbolic of the fact that Conservatives are ignoring areas like this.”

The result is likely to set nerves jangling among Tory MPs in similar “safe” seats across the home counties and add to pressure on the government to rethink the proposed reforms. 

The plans would see councils given set housing targets and told to zone areas which would then grant automatic planning permission to developers.

Locals would not be able to influence planning decisions under the new system, with their input limited to the formation of the council’s local plan before a zoning process begins.

Last month, the Liberal Democrats seized a string of council seats in traditionally Tory areas such as Oxfordshire, Surrey and Cambridgeshire, and in Buckinghamshire took hold of Amersham council within the Chesham and Amersham constituency.