Peter Ricketts says current negotiations will come to look simple as next phase takes hold

The next stage of the Brexit negotiations are going to make the current mess look like a simple affair and will tie up the civil service for years, the former national security adviser and head of Britain’s diplomatic service has warned.

Peter Ricketts’ remarks will alarm those who believe the Brexit cloud hanging over the country will evaporate if only Theresa May can get the EU withdrawal agreement passed in parliament.

A gathering of experts on Brexit and trade negotiations concluded that the bumpiest ride is yet to come, with Britain’s negotiating hand already weakened and EU unity to be tested in trade talks as member states jostle for position.

UK stands down 6,000 no-deal Brexit staff - after spending £1.5bn Read more

At an Institute for Government seminar, Lord Ricketts said the next phase of Brexit would be so complex and time consuming that it would make Theresa May’s current crisis look like “a relatively simple, straightforward affair”.

Ricketts is a former Downing Street national security adviser, former ambassador to France and a member of the House of Lords EU select committee, which has just published a report called Beyond Brexit: How to win friends and influence people.

He predicted negotiations are likely to go on for years and “encompass pretty much the entire of Whitehall”, with detailed negotiations expected in everything from trade and financial services to data transfer, transport, fisheries and nuclear and gas supply.

Tim Durrant, co-author of the IfG’s report Negotiating Brexit, preparing for talks on the UK’s future relationship with the EU, says the forthcoming negotiations will be of a scale and complexity unseen in the UK since the country joined the common market in the 1970s. And those negotiations will look like a walk in the park compared to what is to come, he said.

“Converting the 24 pages of the political declaration into thousands of pages of legally binding text will require detailed work from a huge number of departments and organisations across government,” the IfG said in its report.

At 585 pages, the withdrawal agreement is a tome, but if it is ratified and a free trade deal is to follow the final document is likely to be tens of thousands of pages long with agreement on the tiniest of details.

Stephen Adams, executive director at Global Counsel, says the departure from the EU is the most significant economic demerger since the second world war.

He also warned that any attempt in government to prescribe a type of Brexit, whether Norwayplus or a Canada-style deal, would be a gift to the EU if combined with a parliamentary ban on a no-deal exit.

“There is nothing wrong with red lines, there is nothing wrong with that as all negotiations have red lines, they are there they signal to the other side what is not acceptable. But the thing that makes red lines real is that you can walk away. If you can’t walk away they become red handcuffs,” Adams said.

It means Britain could be looking forward to years of legislative logjams with little oxygen for anything other than Brexit in parliament and the civil service.

It was revealed in January that the impact of Brexit on day-to-day activities was already significant, such that the civil service was hiring about 10,000 people to cope with it.

If May gets her deal, the clock on the trade deal starts ticking again with a series of deadlines hitting.

In June the plan for financial services must be in place while the UK will have to decide by the summer if it wants to extend the transition period by up to two years.

• This article was amended on 14 May 2019. In reporting what Stephen Adams had said the phrase “proscribe a type of Brexit” was used where “prescribe” was meant.