Former MP John Thurso returns to House of Lords after winning election only three people were allowed to vote in

Viscount Thurso was a member of the Lords between 1995 and 1999 ​before being axed as part of Labour reforms

There are 92 hereditary peers still in the House of Lords following New Labour's reforms (Getty)

A former MP has been elevated to the House of Lords as a hereditary peer following an election in which only three people could vote.

John Thurso has won a by-election caused by the death of hereditary peer Eric Lubbock, Lord Avebury, which only existing Liberal Democrat peers could vote in.

Under existing Lords procedures, the 92 hereditary peers can only be elected to the upper chamber by members of their own party.

Viscount Thurso was a member of the House of Lords between 1995 and 1999 before being expelled when New Labour reforms axed most 'hereditary' peers in favour of 'life' peers.

He was then elected MP for Caithness and Sutherland in 2001 and served up until 2015.

The existence of a remaining rump of 92 hereditary peers was seen as a “temporary” compromise by the government at the time to get the reforms through Parliament.

Viscount Thurso was unanimously elected by the Earl of Oxford, the Earl of Glasgow and Lord Addington.

He is the grandson of Archibald Sinclair, a former Liberal Party leader who was a member of Winston Churchill’s wartime coalition government.

Last week, Lord Avebury’s son John Lubbock called for a boycott of the election, calling it “farcical”.

He wrote in the Guardian: "If reforming parties such as the Liberal Democrats want to be taken seriously, they should not embrace the mockery of this anachronistic election.

"Refusing to fill Avebury’s place would be a far more fitting tribute to his legacy.

"At a time when all political parties remain tarnished in the public eye, some moral leadership in boycotting this ludicrous election would have been welcome."