It’s a decision which has been dogged by delays and political procrastination, put off by David Cameron to avoid a political row, and now sits in Theresa May’s in tray. For years it’s been kicked and tossed around, subjected to reviews and study, but now a decision on Heathrow expansion looms large with a decision on a third runway possibly next week.

Given the “thumbs up” by the Airports Commission, Theresa May must now decide to back Heathrow expansion or not. Coming after the Brexit vote and the dithering over Hinkley, it’s a decision which will signal just how serious May and her government are about turning the soundbites of industrial strategy and infrastructure into reality.

It’s a decision which will also signal to the rest of the world whether the UK will continue to be outward looking and open for business in a post-Brexit world. A failure to give the green light to Heathrow expansion would allow the airport’s European competitors to steal a march and diminish its status as a leading global hub.

Sending a message to the rest of the world that the UK is only partially open for business, rival airports like Frankfurt and Charles de Gaulle in Paris would rub their hands and the development of one of the UK’s most important trading gateways would be grounded. Aside from the symbolism of such a decision, a failure to go ahead would see the Government turning its back on a possible £211 billion boost to the whole of British economy over a 60 year period.

This is no small change for a post-Brexit economic road which Theresa May recently described as “bumpy”. Giving the green light to Heathrow would help smooth those bumps, by generating an estimated 180,000 jobs across the UK, and giving our young people the hope of decent work in an uncertain world through the creation of 10,000 apprenticeships by 2030.

A third runway at Heathrow will not just impact on London, but the entire UK. It will allow people to book from Newquay to Dubai, Inverness to Chicago – an international hub is as essential for the growth of our regional and national economies as it is for that of our capital.

Which is why Unite members, whose livelihoods depend on the continued success of Heathrow and the security and jobs that expansion would bring, want to see May give her backing to a third runway. From parking up and checking in, to boarding and in-flight, Unite members ease the passage of people and goods from one of the world’s busiest airports to destinations as far afield as Anchorage and Sydney.

But it’s not just current and future aviation workers and those in associated industries whose futures will be secured. Workers across the whole of the economy, in construction and manufacturing, stand to gain from such a massive project, from primary contractors all the way through to manufacturers in the supply chain across the UK.

With studies showing that a third runway would not breach emission laws because of advances in technology, Heathrow gives the prime minister the opportunity to put her words into action and show what an active industrial strategy looks like. A key component of which must be that if it’s bought for Britain, it’s built by Britain, using domestic manufacturers and steel to maximise the economic dividend and secure decent jobs.

So, to coin her own phrase, I urge Theresa May to “seize the day”. Resist putting up the “closed sign”. Show Britain is open for business and for secure jobs by giving the green light to Heathrow expansion.

Peter Kavanagh is Unite’s London and Eastern regional secretary.