Boris Johnson has been left in charge of the UK

Boris Johnson during Brexit campaigning (Reuters file)
Boris Johnson during Brexit campaigning (Reuters file)

When you go on holiday, others have to step in and fill the gap.

It's just like that for British Prime Minister Theresa May - except the man who's taken the reigns is Boris Johnson.

While Ms May is traipsing around the Swiss Alps, the controversial Mr Johnson is running the country.

Well, sort of. He's been appointed 'senior duty minister' in Ms May's absence, meaning he can attend to urgent business or meetings if required.

However, a Downing Street spokesman has assured potentially nervous Brits that the Prime Minister's still "very much in charge".

That may be a relief to those who are afraid of a leader who'd knock down very young children to get what he wants.

It's just a temporary rise to power for the former-London-Mayor-turned-Brexit-leave-campaigner-now-Foreign-Minister - but it's been met with plenty of trepidation on social media.

A Daily Mirror editor advised people to run for the hills.

While Labour MP Angela Eagle's horror was palpable.

However, Downing Street resident Larry the Cat has stepped up to calm nerves, with his unofficial Twitter account jokingly reassuring that Mr Johnson has to run all decisions past him.