What British Prime Minister Theresa May would give to have a negotiator with Jonathan Powell's experience. As Tony Blair's chief of staff from May 1997 all the way through to his departure a decade later, Powell has been at the heart of deals on the transfer of Hong Kong to China, the Irish/UK Good Friday Agreement and countless EU summits.
But none of them comes close to the Brexit negotiations, which he describes as "the most complex, the most difficult, the most technically challenging" he's ever seen.
To assist in making things that little bit easier, Powell has helped establish Brexit Exchange, a pan-European project to bring the voice of business and industry closer to the negotiations. Along with his co-chair, former German finance minister Steffen Kampeter, Powell hopes to use Brexit Exchange as a 'neutral platform' to promote the voice of business.
"Government can look after its part but what you need is a bottom-up approach, something that builds from the needs of business up to the negotiations. Without this sort of information exchange, Powell argues, bureaucrats risk making fatal errors as the talks unwind.
"I think the real danger of this negotiation is things are done by mistake because the people doing the negotiation don't actually understand how the auto industry works, how the pharma industry works. They make mistakes, and that's where this can contribute."
Businesses themselves also need to prepare themselves for the changes that Brexit will bring, he argues.
"Different sectors are in different stages of preparation - it's clear for example that the financial services sector is zooming ahead and they're already talking about moving people out of London to be on the safe side. But quite a lot of the other sectors in Britain and perhaps particularly in Europe aren't really prepared for this, this isn't very high up their agenda and they're suddenly going to be surprised by it when the negotiations start properly in the autumn after the German elections."
When it comes down to the work of negotiating, Powell reckons bureaucrats and politicians could do worse than heed the words of boxer Mike Tyson. Tyson said 'everyone has a plan when they go in to fight - but it disappears as soon as they get punched in the mouth'. "That's the problem, as soon as Theresa May engages, her strategy is going to collapse, so she needs to be flexible, she needs to be ready to compromise."
So what advice does Powell offer to the beleaguered British negotiators? "The first thing they need is to really get some European expertise in from outside…I would sort of be bringing back some of the old lags who really have done these sort of negotiations in the past to beef up the UK team.
"Secondly, I would really try and work out what my bottom lines are. In negotiating sort of jargon, academics talk about BATNA - Best Alternative to a Negotiated Agreement - and they really need to think through what that is. It's all very well people saying no agreement is fine - it isn't. It would be absolutely catastrophic and that's one of the things that business will tell you if you talk to them."
As for the substance of the negotiations, Powell is particularly concerned about the future of Northern Ireland. The question, then, is whether to bring in customs checks on the border, or between the island of Ireland and the British Isles.
"The basis of the Good Friday Agreement was people in the North could be Irish, could be British, could be both and were free to have their identity. If you start breaking that up by making the border mean something, it's very hard to get backwards and forwards across it, then that will undermine the whole basis of the Good Friday Agreement."
One of the strangest effects of the Brexit vote, he adds, might be to make Unionists reconsider the idea of a united Ireland if it means they can stay in the EU. "What you seem to have now in the North - and I wouldn't exaggerate it - is a feeling among many Unionists, middle-class Unionists in particular, who voted against Brexit, that actually when they come to look at this now maybe it's not such a great idea for their economic interests to stay out of the Republic of Ireland if the Republic of Ireland is going to be in the EU and the single market and they'd be out.
"By the Good Friday Agreement we closed down the idea of a united Ireland at least for a generation and now Brexit's opened it up. We tried to make Northern Ireland boring and the trouble with Brexit is it's going to make it interesting again."
Brexit Exchange will be launched on 18 May, at the Leadenhall Building in central London. For more information visit www.brexit-exchange.com