Back in 2016, 17.4 million people voted to leave the EU. And if today’s rumours about the government wanting to extend the 21-month transition period are true, we still won’t have left the EU way into 2021.

It’s vital we give effect to the referendum result. People voted to take back control of our borders, laws, money and trade. They wanted us to radically transform our country into a self-governing, free-trading nation and for us to build a stronger and more prosperous future outside the EU.

Of course, it’s important that we leave in an orderly fashion. When we formally exit on 29 March 2019, it’s crucial that there’s a smooth path to a future, permanent trading relationship. Businesses understandably need some time to prepare for the new arrangements.

But this must be time-limited. The end of 2020 is already long enough. I see no point in us building a bigger bridge to nowhere. Why would we extend the transition phase when we don’t know where or what we are even transitioning to?

The transition period will only kick in at the end of March next year if we secure a withdrawal agreement. And to secure this, both sides have committed to agreeing an Irish border backstop – an insurance policy designed to prevent the need for customs checks. It is this that is causing the deadlock.

But extending this transition period will not in any way solve people’s concerns about the border in Ireland. If the EU is refusing to help us to solve the border issue now, why would another three years resolve this?

Most importantly, though, this meaningless extension would leave the UK subject to EU rules and paying into the budget while we have no say over how taxpayers’ money is spent. We’d be half in and half out – bound by the EU’s rules, but not able to help shape them.

And then there’s the money. Back in the mid-1980s, when we had influence in Europe, Margaret Thatcher went in to bat for the UK. She demanded “our money back” and secured a rebate for the UK, reducing our contribution and saving our money instead for vital public services.

Now, it seems as though we will just accept anything because we are so desperate to secure a deal. We will lose our rebate (worth £4.5bn a year on average) at the end of 2020 because the EU has, sensibly, planned its 2021-27 budget without us in mind. So if we extend the transition past 2020, we won’t just have to cough up the usual £10bn a year, it will more likely be £10bn-15bn.

MPs are already struggling to justify things to their constituents when they are asked tough questions about budget cuts. If we can’t find the money to fund universal credit, schools, hospitals and other public services, how on earth do we suddenly find an extra £15bn to hand over to the EU for an unnecessary and undemocratic additional year of purgatory?

We’re already being asked to stomach handing over a cheque for £39bn as part of our “divorce” settlement, without having a trade deal agreed in return. The British public simply won’t accept this.

This extension will cost the taxpayer billions more, it won’t provide any reassurance to anyone about Ireland, we’ll be bound by the EU’s rules and be in the single market and customs union for even longer, and it will give the EU even less of an incentive to agree a timely trade deal with us. Nothing will change unless everything changes.

• Priti Patel is the former international development secretary