JOHN Kerr is at the dining room table of his northwest London home, preparing for a long day in the House of Lords, where he sits as Baron Kerr of Kinlochard. Kerr took his place as a peer after a glittering career as the country’s leading diplomat - today, however, he is speaking in rather undiplomatic terms, and that’s because Brexit is on his mind.

The 76-year-old Glaswegian is scathing of the way Britain handled the negotiations - and this is a man who knows about negotiation. As a key member of the European Convention, Kerr wrote Article 50 of the Lisbon Treaty – the clause which triggered Brexit. He was permanent undersecretary at the Foreign Office – making him effectively the UK’s chief diplomat - and he was also our man in Washington and Brussels, serving as Ambassador to the United States and as the British representative to the European Union. He also negotiated the Maastricht Treaty with John Major, securing the UK’s opt out from the euro, and negotiated nuclear armaments for Margaret Thatcher at Nato.

THE MISTAKES

"We didn’t know our foe very well," he says of the negotiations – not that Kerr sees the EU as an enemy, quite the opposite. "We didn’t study the other side. We thought we could have our cake and eat it. We thought they needed us more than we needed them, that we could pick them off one by one, that the deal could be done in Berlin over a weekend."

He speaks incredulously of Brexiteer ministers who "didn’t understand that [the 27 EU member states] would stick together, would stick up for Ireland, would defend the integrity of the single market. These were basic mistakes".

A bigger mistake, though, was that "we didn’t have a clear vision of where we wanted to end up. We didn’t decide how close or far away from the EU we wanted to be". Theresa May, says Kerr, avoided that discussion in Cabinet as ministers would have disagreed –until at Chequers last July when she did put forward her proposals resulting in the resignations of David Davis and Boris Johnson, as Brexit Secretary and Foreign Secretary.

Kerr continues with his withering assessment of May: "She didn’t reach out to Parliament, she’s never tried talking to the opposition to find a common position, she’s never reached out to the country and explained we can’t have our cake and eat it, and she’s never reached out to Edinburgh, Cardiff and Belfast and tried to form a consensus of the four nations."

It was "muddling along", he says. "Getting involved in tactical battles without an overall strategy is a big mistake – and one that we made."

If there’s been worse negotiations in history, then Kerr "can’t think of one at the moment". May’s deal is "very humiliating" and its parliamentary defeat "unprecedented", he says. "With some of my friends in Brussels, it’s quite awkward talking to them now as they’re embarrassed by the scale of their success and our humiliation".

Kerr believes civil servants from the Foreign Office should have played a central role in negotiations. He turns his attention to Johnson, Davis and Liam Fox, the International Trade Secretary. "I don’t think it was a good idea to put Johnson, Fox and Davis in charge of this negotiation," he says. "I think that meant the Prime Minister was slightly cut off from official advice."

In comparison, EU officials involved in negotiations "were professionals who knew the European institutions very well". Kerr says the Foreign Office was cut out as it "was not really trusted because it was seen as having been in the past rather in favour of remaining in the EU".

"A very serious mistake was made putting Mr Johnson in charge of the Foreign Office," he adds, "because the Prime Minister clearly didn’t trust Mr Johnson, but advice coming from the Foreign Office obviously had to come through Mr Johnson and that probably reduces the chances of that advice being listened to."

Kerr points out that "the unity of the 27 has been remarkable, and that’s partly down to us making it easier for them by never coming forward with any proposals at any stage of the negotiation. We always reacted to proposals from the other side. In negotiation, the power of holding the pen is real – if you set the agenda by putting forward the proposals, you don’t necessarily get everything you put forward but you’re off to a good start. The inability to decide in Cabinet where we wanted to end up meant we never actually put a proposal on the table. We made speeches in London but we didn’t put forward any negotiating documents."

WHAT NEXT

Kerr now believes that we are heading "for extra time" – which could only be done through an extension of Article 50 delaying Brexit – and then a second referendum.

"I think the muddle we’re in now is one which can’t be sorted by March 29. I think it may well end up in a second referendum, and I think it should end up in a second referendum as it’s now been established that a lot of the promises made in 2016 can’t be kept, and people have tumbled to the fact that leaving without a deal would be a very serious economic disruption. There’s also been a very clear rejection of the deal that Mrs May brought back. It follows there should either be a better deal or no Brexit. I think we’re probably heading for a second referendum."

Renegotiation is unlikely. "It’s possible a different form of Brexit will emerge from Parliament and be negotiated with the EU," says Kerr, "but I don’t think so. I think the EU isn’t going to make many changes to the deal it spent two years negotiating."

As to how a second referendum would go, Kerr says we are in the lap of the gods. "At present, opinion polls say that if there’s a referendum tomorrow Remainers would win 56-44 but David Cameron was ahead with his remain campaign at the start of the 2016 referendum and he lost."

If he was advising the Government he’d tell them "we’re in a bad mess, the best thing to do is stop and think and ask the people what they want now they can see what leaving means: do they want Mrs May’s deal, no deal – which would be a complete disaster – or do they want to stick with the deal we’ve got, full membership of the EU".

If Britain chose to remain in Europe "no-one could make us pay a price by taking off our rebate or forcing us to join the euro. These threats the leavers talk about, none of them are true. We would pay no price, political or financial, if we decided to stay. So I think we’re heading for a pause for thought, an extension of Article 50, and a referendum."

SCOTTISH INDEPENDENCE

Kerr got involved in the independence referendum because of Europe. "I campaigned against Alex Salmond as I didn’t believe him when he said if we Scots went independent while the UK was in the EU that we’d be allowed to just pull up another chair at the table," he says.

Kerr argued that an independent Scotland would need to apply for EU membership. "I thought that would be perfectly doable, but when Scotland got in it would be on new members terms," he said – that would mean no UK-style rebate. "Scots would therefore be paying more per head that any Englishman," said Kerr.

However, Kerr accepts that "this argument is irrelevant" if the UK leaves the EU – and that means a big part of the Better Together case collapses.

Nevertheless, Kerr remains a strong supporter of the union. "Being members of the UK multiples Scottish influence. If we Scots left the UK, the economic disruption would be even greater than the economic disruption if as members of the UK we leave the EU." He adds: "Economists say the effect of leaving the single market of the UK, in terms of the damage to the Scottish economy, would be five times as great as the damage to the UK of leaving the EU."

Personally, Kerr says, he wants to be "very Scottish, pretty British, and rather European".

NORTHERN IRELAND

Kerr is hoping that peace holds in Northern Ireland amid the destabilisation of Brexit. "We’re in a very dangerous country when we’ve stories like the Government thinking of going for some amendment to the Good Friday Agreement as a way of getting around the need for the backstop," he says.

"The Good Friday Agreement is a hugely important achievement and for 20 years it’s worked and we haven’t had a return to the Troubles. We need to tip toe around this very carefully and I’m not sure all the politicians in London quite understand how fragile the situation is.

"I think it’s also a pity that the Government is relying for its majority on the DUP. I think it’s quite hard to play the role that John Major and Tony Blair played of being the mediator, the honest broker, if you’re relying for your political survival on the support of one party which is very sectarian in its support."

THE FAR RIGHT

Kerr says that a second referendum would "bring some social tensions" with hardcore Leavers angry at another vote, but he feels "the social tensions over time of dragging us out of the EU without giving us the chance to say what we want, now the terms are known, would be even more socially disruptive".

"Young people," he says, "would be deeply resentful if the golden oldies refused them the chance to have another say."

Kerr also worries about the effect of English nationalism on the rest of the country. "It’s the case that in Scotland, Wales and Northern Ireland, that to be dragged out because of an English nationalist vote against the EU would breed resentment unless there was another fair test of what the public as a whole wants."

"You get social tension either way," he says. However, we need to face down the worst of it.

"If you look at the history of countries where right-wing populist movements gained force – say, the history of 1930s Germany – the unwillingness to stand up to thugs, that’s really very dangerous to society. The worst reason for not having a second referendum would be if we were frightened of right-wing populist gangs in the street – you have to take a stand against that sort of thing. We live in a liberal democratic country and people should not be blackmailed or bludgeoned into a particular political course by threats from thugs."

WHAT THE WORLD MAKES OF IT ALL

Kerr knows the corridors of power the world over. Today, governments around the globe are bewildered by the UK chucking away influence and prestige.

"The world doesn’t quite understand what’s going on," he says. "It seems to be some breakdown in the UK." He adds: "The fact we were one of the two most influential states in the EU meant that American presidents listened to us quite a lot as they knew if they could do a deal with us we could probably sell that deal to the EU. It was a multiplier of our influence.

"We were more powerful in Brussels as we were known to be influential in Washington, and we were more influential in Washington as were known to be powerful in Brussels. Our friends in Canberra, Delhi, and Ottawa attached considerable importance to the help we could give them in Brussels, so our friends around the world are a bit confused as to why we would want to give all that up.

"I don’t think the die is yet cast, though. I think we could well draw back – in which case this would be seen as a very odd episode, where we seem to have gone through some sort of crisis but come through it okay.

"If we go ahead and leave the EU I think we’ll pay a price that won’t just be economic – and it’ll be a serious economic price, particularly for poorer people in our society – it would also be political. I think our influence in the world as a whole would shrink."

THE ROOTS OF BREXIT

Few, if any, of the main drivers of Brexit had much to do with Europe, in Kerr’s opinion. First and foremost is "the way the British political machine and successive governments tended to connive with Fleet Street in presenting Brussels as a place of endless battles and ambushes, that Britain was alone against these horrible continentals".

In fact, he says, "we were the most influential state in Brussels. We had more influence on the commission than any other member state, the single market was divised by Margaret Thatcher – but ministers liked to pretend that it was a struggle between the forces of light, the British, and the forces of darkness on the continent".

Secondly, comes the toxic subject of immigration. "Political elites underestimated the effects of immigration on particular bits of the country. Although immigration is very good for the country, it clearly puts strains on health, education and housing in particular areas, and that was ruthlessly exploited by the Leave campaign.

"People’s concern wasn’t with young people from Poland coming to earn some money and then go home, it was more with immigration from the subcontinent, from India and Pakistan, and there was that nasty link made between Muslim immigration and a terrorist threat – a false link in my view.

"EU membership doesn’t in any way restrain what our immigration rules are in respect of non-EU citizens, so if people had wanted to restrict immigration from the subcontinent they could have done so at any time and the EU would have had nothing to say about it."

Finally, there’s the economic component. "The huge wealth of financial Britain, particularly the City of London, contrasted with some left behind bits of the country, and that contrast was deepened by the austerity policies of George Osborne.

"Saying ‘we are all in this together’ sounded good but it didn’t feel like that for people who saw tax cuts for the rich and huge cuts in support for local government, the NHS, education, and the closure of libraries. That too had nothing to do with the EU. It wasn’t EU rules which meant we had to go through austerity, it was the decision after the 2008 crisis that we needed to tighten our belts, and the way we tightened our belt was seen in some parts of the country as pretty unfair."

It’s a pity then, Kerr adds wryly, that the standard bearers for the remain campaign in 2016 ended up being David Cameron and George Osborne.