Step inside a £25 million mansion on London's 'Billionaire's Row'

The Bishops Avenue - otherwise known as 'Billionaires Row' - is one of the most exclusive housing streets in London. It was recently reported that Justin Bieber had begun renting a £108,000-a-month mansion there.

Less recently, residents have included Sir Billy Butlins, the Sultan of Brunei and the President of Kazakhstan.

In an interview with The Observer, Trevor Abrahmson - Managing Director of Glentree Estates - said, "among the wealthiest circles in the world, The Bishop's Avenue is better known than Buckingham Palace."

Despite being one of the most exclusive places to live in the world, The Avenue is hardly out of the way - just a stone's throw from East Finchley underground station. It's also surrounded by some of London's highest performing, most exclusive teaching establishments, including Highgate School and St Margaret's.

Exorbitant streets like The Bishop's Avenue have often drawn criticism in the past for acting as a safety deposit box for the foreign uber-rich, meaning that the opulent houses are often empty and the streets left deserted.

Indeed, during the First Gulf War, a large proportion of the mansions on the road were bought up by the Saudi Arabian Royal Family. In 2013, however, they were sold to LJ Capital for £80 million - driving development of the once muted streets.

The Bishop's Avenue residencies have changed a lot over the years, but they have always retained their incredible luxuriousness.

Take a look inside the £25 million Stratheden house below, complete with a 12-metre indoor swimming pool, spa, and 3,000 sq ft ballroom.