London stands on the brink of a catastrophe, the shockwaves from which would be felt across the country. In just four days’ time, voters in the capital could elect Sadiq Khan to succeed Boris Johnson as mayor.

The greatest city on Earth, which is a global leader in everything from finance to fashion and the seat of the oldest and most respected democracy in the world, would be represented by the man who nominated Jeremy Corbyn for leader of the Labour Party and who has admitted he would do it again.

London’s £600billion economy would fall into the hands of a man who backed Ken Livingstone over his suspension in 2006 for anti-Semitic remarks to a Jewish reporter.

It would mean aggressive socialism entering Britain though the back door.

Devastation: A double-decker bus wrecked by a suicide bomber in the 2005 terror attacks in London

If Khan wins on Thursday, the world’s premier financial centre will be handed to the most hard-Left, intolerant, anti-business Labour Party since the days of Michael Foot. An economy larger than Sweden’s will be run by a party that backs wildcat strikes and flying pickets, wants to turn the clock back to the 1970s, and whose leader has described business as ‘the enemy’.

Khan has flatly refused to rule out hiking taxes, which would deal a devastating blow to the engine room of the British economy.

As a beacon of freedom, diversity and prosperity throughout the ages, London will always be in the cross-hairs of pan-European terror movements.

The number one job of any mayor of London is to keep our city safe.

Yet if Labour wins on Thursday, we will have handed control of the Met, and with it control over national counter-terrorism policy, to a party whose candidate and current leadership have, whether intentionally or not, repeatedly legitimised those with extremist views.

Corbyn has described Hamas and Hezbollah as ‘friends’.

Shadow Chancellor John McDonnell is a self-proclaimed IRA sympathiser.

And the last Labour mayor, Ken Livingstone, has in the past few days shocked even hardened critics of Labour with grotesque comments about Hitler.

Until this week, Khan was happy to parade the fact that Livingstone was endorsing him: now he can’t back away fast enough.

Yet Khan is not running as an independent. He is running as the representative of the most divisive Labour party we’ve seen for a generation. He is running on the back of hard-Left votes he courted in order to win the Labour mayoral selection.

Zac Goldsmith: 'I am standing to be mayor for exactly that reason: to take the success we have seen under Boris Johnson and make it work for everyone'

And he is running with the backing of people like Livingstone, whose offensive views he’s overlooked, time and time again, to further his own career.

Doing whatever it takes to further his own political interests, of experimenting with his principles, is a defining thread of Sadiq Khan’s record in public life.

In 2006 he criticised the decision to suspend Livingstone for comparing a journalist to a Nazi concentration camp guard, and as a lawyer Khan tried to get the banned extremist leader Louis Farrakhan – who described Jews as ‘blood-suckers’ and called Hitler ‘a very great man’ – admitted to the UK.

Khan was recently forced to suspend his aide, Shueb Salar, after The Mail on Sunday revealed that for years he had been making offensive remarks about rape and murder.

In the pursuit of the mayoralty, Khan has cynically changed his position on virtually every issue.

Until recently he was in favour of developing our precious Green Belt; he is now apparently opposed. He was passionately pro Heathrow expansion; he is now against it. He was pro sanctions against Israel; he is now against. He was pro Labour’s mansion taxes; he now opposes them.

He says he’ll be a pro business mayor, but has already promised to set up a dedicated union unity team in City Hall if elected, and is pursuing a Corbyn-backed fares policy that TfL has warned will devastate transport investment and cause London to grind to a standstill.

London’s economy is too big and too important to be a testing ground for a four-year Khan-Corbyn experiment. Five-and-a-half million Londoners rely on it for their jobs and livelihoods.

The choice facing Londoners on Thursday couldn’t be clearer. You can stand against the risk of an unprincipled politician and the madness of Corbyn’s Labour, and instead choose a mayor who will work with this Government, including holding them to account when necessary, to keep our streets safe, keep London moving and growing, and make this an even greater city.

Goldsmith: 'In the pursuit of the mayoralty, Khan has cynically changed his position on virtually every issue'

I am standing to be mayor for exactly that reason: to take the success we have seen under Boris Johnson and make it work for everyone.

There is a huge amount that needs to be done and can be done by the right mayor. I’ve delivered day in, day out for my constituents, and was returned with the biggest increased majority of any sitting MP at the last Election – the best reference any politician can ask for. I’ll do the same for London.

I will work with the Government to build a London that all Britons can be proud of, building 50,000 homes, without trampling on communities or concreting over green space. On my watch, London won’t become a city of empty skyscrapers dumped on reluctant communities. I will build a city rooted in streets and parks and beautiful neighbourhoods, with more homes available for Londoners on average salaries.

My Action Plan for Greater London will make London the greenest and cleanest city on Earth. As mayor, I’ll clean up our buses, cabs and cars. I’ll get even more people cycling safely. I’ll deliver a clean car revolution, ramp up solar energy and give our green spaces the strongest possible protection. I’ll invest in pocket parks in London’s greyest areas so that everyone has access to the outdoors.

My number one priority will always be to keep you safe. I will always fight to make sure the police have the resources and tools they need.

I’ll maintain the Met at its current strength and I’ll put 500 extra officers on the Tube, funded by tackling union perks.

And when our police are called upon to make split-second decisions, they will always have my backing.

There is a huge choice at this election: between business backed or business attacked; taxes frozen and taxes hiked; between four years of bickering, blame and gridlock or four years of a mayor who will put people first.

Just a few thousand votes in each London borough will make the difference.