Meet Maros Sefcovic, the steely former communist who imposed the EU's Brexit deadline

Before he arrived in London on Thursday to set the British Government an end-of-month deadline to drop the Internal Markets Bill, few people in the UK had heard of Maroš Šefčovič.

The towering, basketball-loving Slovak is Michael Gove's opposite number on the joint committee for the implementation of the Withdrawal Agreement.

The committee is tasked with making sure that the provisions of the Brexit treaty – and especially the provisions designed to prevent a hard border in Ireland – are in force and on time on January 1.

When it became clear that the UK planned to breach some of those clauses, Brussels sent for Mr Šefčovič (see video below).

For many in the Belgian capital, the 54-year-old polyglot, who speaks English, French and Russian, was a wise choice. As Jean-Claude Juncker's energy commissioner, he was embroiled in tough trilateral negotiations between the EU, Ukraine and Russia.

The EU is dependent on Russian gas. At the height of the Ukraine crisis, Russia was threatening to turn off the taps of its gas supplies to Ukraine, robbing the stricken country of valuable transit fees and the bloc of energy supplies.

Mr Šefčovič, a socialist who ran unsuccessfully to be president of Slovakia, won plaudits from all sides as he managed to negotiate a solution in highly challenging circumstances.

Dealing with an untrustworthy Russia, some Brussels sources suggest cheekily, is ideal preparation for talks with a UK that goes back on its word.

Mr Šefčovič, a member of the Communist Party before the fall of the Iron Curtain who studied in both Moscow and at Harvard, is seen as a safe pair of hands. He has been praised by officials for his ability to whip through briefings and his laser-like eye for detail.

He is well known for his cheerful, friendly approach and has an unfailing habit of referring to Mr Gove (see video below), the Chancellor of the Duchy of Lancaster, as either "Mike" or the "Chancellor".

However, when he arrived in London he was all steel, warning that Britain needed to rebuild trust and that the EU would not be shy in retaliating if the Internal Markets Bill was passed.

A big hitter in the EU's de facto capital, where he has served as Slovakia's commissioner under three commission presidents since 2009, he has risen to be commission vice-president for inter-institutional relations and foresight.

Whether or not Mr Šefčovič, or "Big Maroš", saw this latest Brexit crisis coming, he will be a well-prepared and formidable opponent for Mr Gove.