The decision of the Supreme Court that Brexit must not be initiated without Parliament's approval has led to fears it could take the Government two years to start the process of leaving the European Union.
Geoffrey Robertson QC, a leading constitutional lawyer, said the court's ruling was a “momentous reaffirmation” of the sovereignty of Parliament.
Prime Minister Theresa May has said she expects to trigger Article 50 - the formal procedure for leaving the EU under the Lisbon Treaty - by the end of March.
However, Mr Robertson said that the necessity to go through the complete parliamentary process - which would involve the House of Lords as well as the assent of the Queen - means that this may not be possible until 2019, just one year before the next general election.
Triggering Article 50 would enter the UK into negotiations with the other EU states. This process is likely to take up to two years - after which the UK would leave the EU even if no agreement on trade, movement of people, etc, had been made.
This means Brexit might not actually take place until after the next general election, which would then become a hugely significant campaign.
