It’s always something of a lottery who you end up living beside at university.

For Keith George, an American student at Oxford in 1983, it turned out to be the future emperor of Japan.

The crown prince, now Emperor Naruhito, was in the room next door at Merton College.

“It was a little bit of a surprise, but we became instant friends,” says Keith, speaking from West Virginia where he now works as a lawyer.

More than 40 years later, Emperor Naruhito is going back to his old student haunts while on a state visit to the UK.

Keith, from the Appalachian mountains and who liked to play bluegrass music, gave the young Japanese prince a chance to see a different life to the Imperial Household.

There were no titles or standing on ceremony. “He asked me the first day to call him Hiro,” says Keith.

Having a royal in the room next door also meant getting to know the prince’s security detail, who had to tag along if they were going to the pub or a restaurant.

“I became very good friends with them too,” says Keith.

The Emperor of Japan and the American lawyer have stayed in touch – including the crown prince visiting Keith and his family in Morgantown, West Virginia.

As thanks for putting up the prince in their house, Keith’s mum and dad were invited to a state dinner in Washington DC, with Ronald Reagan and George H Bush.

But what Keith remembers is the brief chance of an independent life that being a student gave to the emperor.

“One of the greatest luxuries we can have is personal freedom,” says Keith.

That was even down to details “like going for a pizza when he wanted”.

In the UK the crown prince could move around relatively anonymously and Keith said his royal friend “adored” being able to go out so informally and without attracting attention.

“He loved the landscape around Oxford, enjoyed the pubs and the restaurants,” says Keith.

“He loved to laugh, he wanted to have an authentic student experience,” he says, remembering their friendship.

That included the Japanese prince playing a viola along with the US student’s bluegrass band.

While the state visit has seen the red carpet rolled out for Emperor Naruhito, including a state banquet at Buckingham Palace, he might be looking forward to the chance to remember the friendships of his student days.

“I knew who he was, I respected that, but our friendship had more to do with who he was as a person. I wasn’t a friend [just] because at the time he was the crown prince. It was authentic,” said Keith.

Now both men are in their 60s and Keith would like to see their daughters meet and continue the friendship for the next generation.

And he looks back with great fondness on such a longlasting and unexpected connection.

“I can say my really good friend the Emperor of Japan.”