Michel Barnier at the EU Commission headquarters in Brussels June 6, 2012. Reuters LONDON — The European Union's official response to Prime Minister Theresa May triggering Brexit states that Article 50 can be reversed, meaning Britain could, in theory, change its mind at some point in the two-year negotiation process.

Britain's ambassador to the European Union Sir Tim Barrow gave the Article 50 letter of notification to the European Commission shortly after lunch time on Wednesday, meaning Britain's formal departure from the 28-nation bloc is now officially underway.

According to a report in The Guardian, a leaked European Parliament resolution, in which EU Brexit negotiator Michel Barnier played a major role in putting together, says that the UK will be able to revoke Article 50 before it expires.

The resolution states that the UK will be able to revoke its Article 50 notification but this process must be "subject to conditions set by all EU27 so they cannot be used as a procedural device or abused in an attempt to improve the actual terms of the United Kingdom’s membership."

However, the resolution makes clear that Britain cannot use the revocability of Article 50 as a means of improving the Brexit package it agrees with EU or for any other tactical purpose.

The key line can be found on page four of the document titled Draft Motion For A Resolution. It's highlighted here:

Britain's judges have not ruled on whether Article 50 is revocable but the Supreme Court ruled earlier this year that Parliament must vote before Brexit is triggered on the understanding that Article 50 cannot be revoked.