Former Conservative MP Zac Goldsmith will fight the Richmond Park by-election on 1 December it has been confirmed.
Goldsmith will be standing as an independent in the competition after dropping out of the Conservatives in protest over the decision to expand Heathrow.
He will face no opposition from either the conservatives or Ukip after both parties declined to field a candidate, with the latter explicitly backing Euro-sceptic Goldsmith's candidacy.
The Lib Dems will definitely enter the competition, having come second at the General Election in 2015, and Labour looks set to follow suit, despite the protests of two of its frontbenchers.
It comes after Tim Farron's party secured a substantial swing away from the Conservatives in David Cameron's former seat of Witney, and the Lib Dems are hoping to go one step further in Richmond Park to defeat Goldsmith.
The former Tory MP has sought to position the by-election as a referendum on Heathrow, but the Lib Dems are trying to make it all about Brexit, having repeatedly labelled themselves as the UK's pro-Europe party after the referendum, and while Goldsmith campaigned for a Leave vote, Richmond Park had one of the strongest Remain results in the country.