Britain's ambassador to the EU has resigned, the Government has confirmed.

But what does the little-known role do, and what does Sir Ivan Rodgers' resignation mean for the UK's Brexit process?

Who is Sir Ivan Rogers?

He was the Permanent Representative to the European Union, known informally as “Britain’s ambassador to the EU”. He was appointed to the job in 2013 by David Cameron.

He leads a team in Brussels called the Permanent Representation to the European Union, known to eurocrats as “UKRep”.

What did he do?

The team he leads is in charge of explaining British policies to the various pillars of the EU – the European Commission, the European Parliament and other EU member states.

He also sits on the catchily-named “Coreper II” committee, or “Committee of the Permanent Representatives of the Governments of the Member States to the European Union”.

That committee draws up the agenda for the European Council – which is when Theresa May, Francois Hollande, Angela Merkel and all the other heads of EU states and governments meet together.

There’s also a “Coreper I” but it’s less important.

Why did he step down?

The Government says he was going to step down anyway in November, and that his early departure will mean that one person will be in charge of the Article 50 process (starting in March) from the very beginning until the end.

He previously told ministers it could take 10 years to negotiate a free trade deal, apparently suggesting a distance between his own views and those of the more “optimistic” Brexiteers around Theresa May.

A former top civil servant Nicholas Macpherson said Rogers had been frozen out of the loop and that this all amounted to a “wilful and total destruction of EU expertise”.

What is the effect of this?

It’s difficult to say. Rogers was supposedly going to leave anyway, so in that sense, not a huge amount.