Steve Baker is co-Chairman of Conservatives for Britain and is MP for Wycombe.

This referendum on the European Union is about the long-term constitutional future of our country. As Conservatives, we fought hard at the last election, and some for many years before, to give the British people the chance at last to have their say.

I will not pretend the EU debate could be without its ferocious moments: we always expected this to be a passionate contest. What I did not expect was how quickly the Remain campaign would descend into insults, personal attacks and petty tabloid smears on key people.

This is not the debate we were supposed to have. It is not the one that the British people expected to be treated to. At the beginning of the campaign, the Prime Minister urged his Cabinet colleagues in a personal minute to act as a “united, harmonious, mutually respectful team”.

That’s why the last few weeks have been so breathtakingly disheartening. I was appalled that such a distinguished figure as Lord Heseltine was used by Downing Street to attack Boris Johnson and convert the debate into one on personality not policy. I understand why Number 10 were alarmed by Boris’s attack on corporate fat cats after the shocking Serco leak and the cheers he received from the people of Stafford. However, it is deeply dangerous for Remain campaigners in Government to make this a debate about the future leadership of the Conservative Party.

They give the impression that they are anxious they are losing the arguments. They appear stuck in a corner, lashing out at their opponents, not making the positive case for UK policy based on EU citizenship, the supremacy of EU law, a common EU trade policy and all the rest.

In another recent example, the Chancellor claimed anyone who takes a different view to his own is “economically illiterate”. Of course that would include two distinguished former Conservative Chancellors, Lord Lamont and Lord Lawson, as well as David Cameron’s predecessor, Lord Howard. Those of us who owe the transformed prospects of our childhoods to these figures would not have them treated so contemptuously.

There is nothing economically illiterate about wanting to take back control of our own finances, taxes and whether we must pay bills the Prime Minister refuses. By even the most cautious of estimates, we send a huge amount of money just to remain a member of the EU: roughly £20 billion a year gross and £10 billion a year net. Just half our daily net contribution would clear my local NHS Trust’s annual deficit this year. I know where my constituents would have us spend this money.

Sir John Major has warned we risk “fuelling prejudice” simply by talking about the consequences of uncontrolled immigration.

Sorry, but no, Sir John. On our side this has been a sober and fair discussion about the inability of the UK to control the volume of people who come and the blatant discrimination that non-Europeans face today as a consequence of the European citizenship which Sir John’s Government signed us up to. By leaving the EU, the UK could have a fairer immigration policy, enjoying democratic consent, based on British citizenship and objective criteria, not merely country of origin.

There have also been intolerable media smears against our leading figures and their families. It is a dark day indeed when Conservatives believe that the centre is behind such vicious briefing.

We are today the only party capable of governing this country. We are the only party capable of saving it from the calamity that would be a hard left, socialist government under Jeremy Corbyn. As the Prime Minister said himself when he ran for leader of the party, it is when we are united and focused that nothing and nobody can stop us.

It was with that strength of purpose that we, as Conservatives, achieved our historic mandate from the British people 12 months ago. In doing so, we were given a clear set of instructions: to deliver on the promises we made in our manifesto. A respectful, decent and honest referendum on the EU is what the British people expect us to deliver and it is what we must have to ensure that disagreements do not turn into deep divisions.

If we’re to come together after this referendum, personal nastiness must end now.