Brexit will test the UK's political, bureaucratic, constitutional and legal systems "to their limits - and possibly beyond", a report has warned.
The Brexit and Beyond report warns that the process of withdrawal from the EU will place "enormous pressure" on Parliament, the civil service and the courts over many years and will put the fabric of the British constitution "under strain".
Withdrawal negotiations under Article 50 of the EU treaties, coupled with talks to establish a new trading relationship with Europe and the rest of the world, will represent the biggest challenge the civil service has faced, imposing an "immense workload" on Whitehall.
And Parliament will "have its work cut out" dealing with the volume of work resulting from Theresa May's decision to use a Great Repeal Bill to abolish the 1972 European Communities Act and transpose all relevant EU law on to the UK statute book.
It will be a "daunting and time-consuming task" to identify and transpose relevant EU rules into UK law, before going through the legislation to decide which parts to amend or repeal, said the report, written by the UK in a Changing Europe group for the Political Studies Association.
The Bill will impinge on the balance of power between Westminster and devolved parliaments, increasing policy divergence in areas ranging from agriculture and fisheries to the environment and higher education.
The group's director, Anand Menon - professor of European politics and foreign affairs at King's College London - said: "Article 50 negotiations will be tricky and hideously technical, but that is the easy bit. When it comes to the crafting of a future relationship, almost everything is up in the air.
"Brexit thus has the potential to test the UK's constitutional settlement, legal framework, political process and bureaucratic capacities to their limits - and possibly beyond."
Prof Menon dismissed accusations that those raising concerns about the possible impact of EU withdrawal were "Remoaners" determined to talk Brexit down.
"An irritating aspect of the current debate is the tendency of Brexiters to accuse those who warn of difficulties of 'talking Britain down'," he said. "It's a good line but a pathetic argument.
"Since when was rational debate a bad thing? Forewarned, surely, is forearmed and this report will help identify potential stumbling blocks ahead."