Theresa May ought to abandon her Brexit challenge in the Supreme Court and put Article 50 to a vote, according to the former Conservative MP Zac Goldsmith, who is fighting the Richmond Park by-election as an independent.

Speaking to The Independent Mr Goldsmith said while it was “frustrating” not knowing the Government’s plans for leaving the EU he defended Theresa May for keeping her card close to her chest.

He added: “I think they should accept it and I think there should be a vote in Parliament. I’m pretty sure that vote would go through very easily – there’s very little opposition in voting for Article 50 so as far as I’m concerned the Prime Minister should do that and not spend months bickering with judges.”

Mr Goldsmith also vowed not to return to his former party before a general election. He was, however, more reluctant to dismiss the idea of re-joining his former colleagues entirely.

While he said, if elected, he would remain an independent for his “full term in Parliament”, he added: “It’s not clever to start planning two or three elections ahead because I’ve got a battle in my hands getting over this line.

“If I’m elected as an independent I will stay an independent – I don’t believe people should switch parties without going back to their electorate.

“I’m standing as an independent and will be an independent for this term. No one makes commitments two elections in advance, it’s pompous and it’s absurd and presumptuous to do so, so I’m not going to. It’s absurd for a politician to start talking about two, three, four elections into the future. I am standing as an independent – if I’m elected I will be an independent for the full term. I don’t even know if I’ll be standing in any further election.”

In ten days’ time voters in the Richmond Park constituency will head to the polls, following the decision by Mr Goldsmith to resign from the Conservative party in protest at Theresa May’s backing for the expansion of Heathrow airport. He has been a vocal critic of the plans for the past decade and promised his affluent constituents he would trigger a by-election long before he was elected six years ago.

Mr Goldsmith's resignation means he has no access to the infrastructure or the data available through the Conservative party machinery in the constituency. He’s had to build his campaign “from scratch” he adds.

“I’ve had a lot of help, a lot of volunteers and in a way it’s a good thing because we are knocking on doors in a completely random manner as opposed to following any old formula. That gives us a much more honest picture of what people are thinking locally. It’s obviously a big challenge, we’re up against a national party machine but, so far, it’s been very positive – it’s going well.

But his old colleagues, and friends in the party have not been totally absent in the campaign. Just last week he was photographed with Conservative MP Jacob Rees-Mogg and the former Northern Ireland Secretary Theresa Villers. Mr Goldsmith is hopeful more will join him on the frontline in the final stretch of campaigning in the by-election. Current Cabinet ministers, including his friend the Foreign Secretary Boris Johnson, however, have been blocked by Downing Street from l¬ending a hand in the fight.

“I’ve had lots of support from local Conservatives,” he added. “After I resigned they had a meeting and sent a message back to the party nationally to say they were backing me in the campaign irrespective of whether there was an official Conservative candidate. As a consequence, the party took the pragmatic view that it’s probably not a good idea to put a candidate up.”

But while the constituency is considered a safe Tory seat by many – Mr Goldsmith received 58 per cent of the vote share compared with 19 per cent for his closest rival in 2015 – the Liberal Democrats are making a concerted effort to retake the seat, which was held by them until 2010. The party leader Tim Farron has travelled to the constituency every Wednesday morning since the announcement of the by-election.

Zac Goldsmith: Heathrow runway will be a 'millstone around the Government's neck'

As Mr Goldsmith attempts to focus the campaign on Heathrow, the Lib Dems are rallying around Brexit in the constituency that voted 72 per cent to Remain at the EU referendum. It is quite clearly the dividing line between the two candidates (both of them oppose Heathrow expansion) and it is one the Lib Dems are exploiting. “The by-election here is a clear choice between two candidates with very different views on Brexit,” claims the party’s campaigning literature handed out to commuters outside Richmond station on one Wednesday morning.

Speaking to The Independent their candidate Sarah Olney, an accountant who joined the Lib Dems 18 months ago following the party’s catastrophic general election result, said Conservative voters in the constituency, who had voted Remain at the referendum, have already promised to vote for her.

She added: “When Zac Goldsmith stood down he wanted the campaign to be a referendum on Heathrow but we started campaigning on the basis as we thought that is what people wanted to hear about. But time and time again people were saying they care about Heathrow… but what I really, really care about is Brexit – that’s what is really upsetting.

But the focus on Brexit is clearly irritating Mr Goldsmith’s campaign – shortly after our interview his publicist calls to suggest the questions were “unfair” and that there was no focus on Heathrow.

“The Lib Dems have been massively downplaying how important Heathrow is in this area,” Mr Goldsmith added. “But I think they’ve misjudged that and of course there are lots of other issues. People know that the election is happening for only one reason and that is because of Heathrow expansion. Most people appreciate the fact I kept that promise and the impression I’m getting is that there is a big appetite among constituents to use this to vote against Heathrow.”

As far as I'm concerned the PM should [hold a vote on Article 50] and not spend months bickering with judges Zac Goldsmith

He continued: “But I’m not sure there’s an appetite to re-run that referendum and that’s what the Lib Dems are hoping. I don’t think there position really adds up. My view is that I didn’t campaign on the issue but I voted Brexit. I think it would be very dangerous to try and stop Brexit,”

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Mr Goldsmith also accused his Lib Dem rival Ms Olney of U-turning on Brexit, claiming before the by-election she was “quite emphatic that there should not be a re-run of the referendum”. The official position of the party is that there should be a second referendum on the terms of Britain’s exit from the EU. If this isn’t granted Mr Farron will instruct his MPs to vote against triggering Article 50.

“The fact that she has completely turned her position on its head in a matter days purely to scrape up a few votes in the area I don’t think goes down that well with a highly-political and educated constituency. I think it looks cynical, and it is cynical,” Mr Goldsmith added.

His campaign in Richmond Park, however, follows an unsuccessful bid for London mayor, in which critics, including some Conservatives, branded his tactics against Sadiq Khan as “racist” and “disgusting”. Asked whether he believed the controversial campaign would have any negative effect on the upcoming by-election, he responded: “The outcome of the mayoral election in this part of the world was a good one. It may not have been for the whole of London…no mayoral candidate has done better in the mayoral election in this part of the world than I did.

Does he regret the tactics used in the campaign? “I regret losing the race because I had an exciting plan I’d put a lot of work into developing a programme for London. My manifesto was brilliant – I didn’t write it myself which is what allows me to say that.

“But I hope the incumbent, the current mayor takes the best bits and uses them because there’s some good stuff there.”

Ms Olney said that while the campaign “did damage his reputation” but said she has deliberately not made it part of her campaign. “We should aim for a better politics,” she added.

The by-election has also proved to be a useful experiment in the concept of a “progressive alliance” – and the obstacles it faces. Despite suggestions from senior figures in the Labour party to test the concept with the Lib Dems and not field a candidate, they eventually chose Christian Wolmar – a former contender of the Labour nomination for mayor of London.

In pictures: 70 years of Heathrow Show all 22 1 /22 In pictures: 70 years of Heathrow In pictures: 70 years of Heathrow Inside one of the terminal tents in 1946 The year the airport opened. Comfortable armchairs and flowers try to distract from the conditions Graham Bridges collection In pictures: 70 years of Heathrow An aerial view of the airport in 1949 Construction of the runway layout and Central Area are under way In pictures: 70 years of Heathrow A Pan Am crew checks out the Boeing Stratocruiser N1029V Clipper Golden Eagle in 1954 During the early 1950s, Pan Am and American Overseas Airlines operated Statocruisers into London Airport in direct competition on the North Atlantic route operated by BOAC In pictures: 70 years of Heathrow One of the first official London Airport guidebooks C.1953, priced 1s In pictures: 70 years of Heathrow In 1950 a permanent concrete terminal building was built This replaced the tents previously used at London Airport North and is seen still in use for charter and cargo flights in this 1959 view via Graham Bridges In pictures: 70 years of Heathrow BOAC check-in desk in 1954 Inside the new London Airport North terminal building, just before the move to the Central Area Graham Bridges collection In pictures: 70 years of Heathrow Air traffic control tower in the 1960s Inside the visual control room CAA Archives via Pete Bish In pictures: 70 years of Heathrow Rear cover of the 1956 guidebook Showing a plan of the airport at the time, with entrance prices to the spectators’ viewing terraces and for airport coach tours In pictures: 70 years of Heathrow Spectators in 1958 How close can you get? As soon as the Central Area was open, spectators were afforded unprecedented views of the airliners In pictures: 70 years of Heathrow Terminal 3 was opened as the Oceanic Terminal on 13 November 1961 It was built to handle flight departures for long-haul routes. Renamed Terminal 3 in 1968, it was expanded in 1970 with the addition of an arrivals building In pictures: 70 years of Heathrow Inside Terminal 3 in 1969 Check-in desks for BOAC and QANTAS airlines In pictures: 70 years of Heathrow Plane spotting on Heathrow’s viewing terraces in the 1960s Wrap up warm, take your spotting logbooks, pen and binoculars and get your mum to pack your sandwiches In pictures: 70 years of Heathrow No 1 Passenger Building Also called the Europa Building. In this photo, taken on 22 June 1963, flags of the many airlines it serves are flown Lee Holden In pictures: 70 years of Heathrow Luggage-trailer-towing Routemaster buses When BEA and BOAC merged to form BA on 1 April 1974, both fleets had to be repainted in the new livery, but so did all the ground support equipment In pictures: 70 years of Heathrow The entrance to the traffic tunnel in 1974 A Lufthansa Boeing 737 is seen on the runway In pictures: 70 years of Heathrow A 40 per cent scale model of Concorde In September 1990 it was erected on the roundabout at the entrance to the tunnel that passes under the northern runway at Heathrow Airport. It was built in four main parts, with an 80ft-long central fuselage section, to which the wings and tail fin were attached. The completed model was placed on the roundabout in September 1990 and was monitored by CCTV and surrounded by an infrared perimeter alarm that was connected to the local Heathrow police station to ensure it was not vandalised In pictures: 70 years of Heathrow Heathrow Airport's 50th anniversary On 2 June 1996, Heathrow marked its anniversary with a flypast of representative airliner types that have served the airport over the years. This culminated in a formation flypast by Concorde with Hawks of the RAF Red Arrows aerobatic team In pictures: 70 years of Heathrow The roof of Terminal 3’s car park One of the last bastions for plane spotters and spectators was here. This is the unfriendly notice that greets anyone who attempts this today Richard Vandervord In pictures: 70 years of Heathrow On 24 October 2003 BA withdrew its Concordes from service The final scheduled commercial flight was BA002 from JFK operated by G-BOAG. Here we see three of the Concordes parked together outside the BA hangar on 8 November 2003 following withdrawal John Hughes In pictures: 70 years of Heathrow The new control tower Costing £50 million to construct, it gives controllers an excellent 360-degree panoramic view NATS photograph In pictures: 70 years of Heathrow The new Terminal 2 The Queen’s Terminal In pictures: 70 years of Heathrow Looking due west down Runway 27L

And Ms Olney appeared relieved there was a Labour candidate. “It’s a tough one because between us and Labour there are large differences on policy. I don’t want to be standing in this election as a representative of Jeremy Corbyn. I think I’m more comfortable that they are standing as a general rule… I’m not Corbyn’s candidate,” she said.

The local Green party decided not to contest the seat but Ms Olney rejected there was any deliberate attempt to form an alliance. Ukip, which came fifth in the seat at the general election last year, also decided not to put a candidate and endorsed Mr Goldsmith for the job.

While Mr Goldsmith appeared confident he will remain the representative for the constituency, he added: “It’s a battle, clearly.” One of the latest polls by BMG for the London’s Evening Standard newspaper found Mr Goldsmith was on course for a solid 56 per cent of the vote – down by just two points from the last general election.