Image copyright PA Image caption Sarah Olney (centre) was confirmed as the Lib Dem candidate at a party meeting

The Liberal Democrats have confirmed Sarah Olney is to be their candidate to run against Zac Goldsmith in the Richmond Park by-election.

Mr Goldsmith quit as a Conservative MP in protest at the government's backing for a third Heathrow runway and will contest the poll as an independent.

The Conservatives and UKIP have said they are not fielding candidates.

Ms Olney said overturning Mr Goldsmith's 23,015 majority was "incredibly doable" for her party.

The Lib Dems, who held the south-west London seat until 2010, finished second in the 2015 general election.

Mr Goldsmith has said he wants the vote, on 1 December, to be a referendum on the government's decision to back a third runway.

But Ms Olney, who also opposes Heathrow expansion, told Sky News Brexit - which Mr Goldsmith backed, unlike most Richmond voters - would "obviously" emerge as another campaign issue.

Party decision

The 39-year-old accountant, who had already been lined up to contest the next general election for the party, was confirmed as its by-election candidate at a party meeting on Sunday.

Labour will field a candidate, despite calls from some of its MPs for it to stand aside to maximise the chances of Mr Goldsmith being defeated, with applications closing on Monday.

Despite their differences on Heathrow, the Conservatives are not standing against their former MP, describing him as a "hard-working champion" for the area.

But the party's decision was criticised by one of its MPs, Alec Shelbrooke, who told Sky News: "I have said quite openly that I think it's a big mistake the Conservative Party is not putting forward a candidate.

"Let's be clear: Our majority will be cut from 12 to 10. Zac Goldsmith does not cut it to 11, it cuts it to 10 because he will be an opposition MP.

"The Conservative Party will lose the Richmond by-election because we do not have a candidate and I think that is wrong."