Interestingly, the exit clause was brought about, and only just by a woman labour MP. 'It is a fitting quirk of history that the 264 words shaping Britain's divorce from the EU were brought to life by British representatives over the objections of federalist colleagues who warned of trouble ahead.
The now-infamous Article 50 triggered by Prime Minister Theresa May came about as part of a grand convention, undertaken between 2002 and 2003, to write an overarching constitution for the EU as it prepared to enlarge deep into eastern Europe.
Looking back today, delegates to the convention recall the rancour that surrounded the very idea of an "exit clause", which was unprecedented in EU law.
"Most people thought the notion that you might ever want to leave was an utter insult," said British lawmaker Gisela Stuart, who was part of the convention's 13-strong executive "praesidium".
The Labour MP fought hard for the exit clause at the convention, noting that it was touch and go whether it would be retained when delegates held their final negotiating session in July 2003.
The convention ended, to the sounds of champagne corks popping and Beethoven's "Ode to Joy", with the clause intact.
Stuart did not share in the joy.
She went on to take a starring role in the pro-Brexit campaign that culminated in last year's referendum decision by voters to make Britain the first country to take advantage of Article 50.
Her revulsion at the EU grew out of what she felt was the elitist spirit of the convention, but was fuelled particularly by later events.
The EU's enlargement did take place, in 2004, but the proposed constitution was then thrown out by French and Dutch voters in referendums'.