Given that Tony Blair ousted John Major from power in 1997, they are hardly ever likely to be best buddies. But for both Prime Ministers, Northern Ireland was a big priority, and the progress to peace there one of the best examples of what boldness and courage, political commitment and hard work, can do.

So as the EU referendum nears, it is good for the campaign that they are going there together, and that their voices will be heard on a subject on which all too little has been spoken, namely the potential impact on Ireland north and south of a LEAVE vote on June 23.

Doubtless they will be drawing attention to the possible return of  controls at what is the only land border between the UK and the EU. Add in the possibility on the other side of the UK, South East England, of the border at Calais moving back to Kent (another issue on which LEAVE are conspicuously quiet) and you start to get into the nitty gritty of just two of the many difficult and unintended consequences of exit.

Border controls in Ireland have a resonance unlike no other. We in Great Britain have not had to live with the kind of checks that the security situation, the smuggling and the organised crime related to terrorism, demanded. Nobody from LEAVE has been able to explain how they can meet their promises to curb freedom of movement by EU nationals without strict border controls returning. Nor have they been able to explain how they would make up for the damage done to both UK and Irish economies by the departure from the single market on which so many of our jobs, and so much of our prosperity depend.

One of the most remarkable parts of the Boris Johnson/Michael Gove et al con trick at the heart of LEAVE has been the way they have turned the concept of the ‘expert’ on its head, and also how they, as Establishment as they come, have become self-appointed leaders against ‘the elite.’ ‘Expert’ used to mean someone who knew what they were talking about. So when nine out of ten economists argue strongly for REMAIN, and when every major economic institution bar none comes out against LEAVE, warning of potentially cataclysmic consequences, these are all dismissed, by Eton/Oxbridge/Telegraph/Tory MP/London Mayor Johnson, and Oxbridge/Murdoch press/Tory MP/Lord High Chancellor Gove as pro-establishment Project Fear flunkeys.

Sometimes, when you have difficulty making a decision, expert opinion is the one worth listening to. When it comes to the peace process, its strengths and weaknesses, you don’t have many greater experts than Tony Blair and John Major. If leaders have a genuine fear that a course of action will have bad consequences for something as important and at times as fragile as the peace process, they have a duty let alone a right to say so, however much the Project Fear attack goes up. There is a lot to be scared about. They will also be warning of the danger of a second Scottish independence if the UK votes to leave and, as I have said before, I think in those circumstances there could be a different outcome.

So yes, the economy is on the ballot paper on June 23, and the single market and the three million UK jobs that partly depend on it should be argument enough to stay. But the peace process is on the ballot paper too. And so is the Union.

They are the kind of issues too serious to be sacrificed on the altar of Boris Johnson’s ambition to follow in the footsteps of Major and Blair into Downing Street. I hope today is one of those days when people really stop and think what is at stake.

I know from my regular visits to Ireland that the business community there is if anything even more united for the UK staying than business is here. Today Ibec, a group representing Irish business, is launching a poster campaign at Dublin Airport, aimed at the many UK voters, and Irish voters with UK connections, passing through there daily.

The message is simple … ‘DON’T GO. Let’s work together.’ Ibec CEO Danny McCoy says: ‘If the UK votes to leave, not only will the UK economy suffer, Ireland will also be badly affected. An EU without the UK would be a lesser Union.

‘A UK exit would send Ireland, Britain and Europe into uncharted and treacherous waters. The value of sterling has already fallen significantly, a vote to leave would prompt a further significant depreciation, heaping pressure on businesses trading with the UK. This is in addition to the countless other risks that would arise during and after the period of a negotiated exit. A UK departure would be a blow to the Irish recovery and result in a protracted period of uncertainty. It would undermine Europe’s ability to act collectively and decisively in the world and would push the EU back into a damaging period of crisis management, at a time when it should be looking to the future.’

While Johnson, Gove, Farage et al blithely claim new trade deals will be worked out quickly and with ease, anyone with any experience of actually doing them knows how untrue that is. We are set, if we leave, for years of uncertainty and with it massive economic risk.

In this era of disbelieve, and of anti-politics and anti-business, and anti-expert, it is easier than it should be for a Trump or a Johnson to gain traction. But sometimes it really is worth listening to people who know what they are talking about. Love them or hate them, Major and Blair are seriously worth listening to on the fragility of the peace process. And the overwhelming volume of the expert voices warning of economic calamity are worth heeding too, because the prospects of it are all too real.