It took the British government nine months to come up with a letter saying "we’re leaving the EU".
Now they think they can negotiate the terms of their disengagement from 44 years of European Integration, sort out the financial implications of ending their membership of the EU and negotiate a "deep and special partnership that takes in both economic and security co-operation" with the remaining 27 states, all in under two years.
On Wednesday 29 March, the British delivered a six page letter to start the Article 50 Process. But article 50 also requires the EU side to come up with a set of guidelines for negotiating and concluding a deal on British withdrawal.
The 27 Governments got a draft of those guidelines on Friday 31 March. They will be shaped at meetings before and after Easter by officials, before going to heads of government for sign off on April.
The European Commission will use them to work up a very detailed negotiating brief in May, and start talks with the British by early June.
Brexit Negotiator Michel Barnier has said he aims to wrap up the Brexit talks by October of next year, to allow six months for ratifications, so in reality, there is less than two years negotiating time before Britain is out.
There are two separate deals to be struck. The first is the terms of Britain's departure from the EU, including settling Britain's outstanding bills. Relatively speaking, this is the easier bit.
The second deal is the future relationship between the EU and Britain once it has left the Union. This is much more complex, as it deals with detailed things like rules and regulations on trade, customs and borders, and formal co-operation between the EU and Britain on a range of policy issues.
The EU 27 say the deals will be done one after the other, starting with the terms for leaving. And that's the deal Mr Barnier aims to wrap up by autumn next year.
In her letter, Mrs May said Britain wants to negotiate the two deals at the same time - the terms for leaving the EU, alongside a comprehensive trade deal and new defence, security and policing arrangements.
She thinks doing all this in two years is difficult but manageable, but the EU says its just way too much to do in a short period.
And besides, Article 50 itself sets out the legal path to be followed.
.@seanwhelanRTE – Two years not enough for Brexit talks https://t.co/fqCL1J8wJR pic.twitter.com/p9ZX2KTcIV
— RTÉ Business (@RTEbusiness) March 31, 2017
First negotiate the terms of Britain's departure then negotiate Britain's new deal with the EU (which has to be carried out under the terms of another treaty article - 218(3) - which covers negotiations between the EU and 'third countries', that is countries that are not members of the EU).
This was made clear by European Council President Donald Tusk in his statement on Friday morning, when he introduced the draft negotiating guidelines.
