Mark Horton is an IT worker from Watford, a town north-west of London.

He happens to share a strikingly similar name to the newly-minted Olympic 400-metre freestyle champion, Australian Mack Horton.

Mack Horton - not Mark - in the pool in Rio. Credit:Getty Images

And for that coincidence, he's paying a high price.

"Luckily I don't speak Mandarin," the 36-year-old Englishman said, after a case of mistaken identity saw a relentless torrent of online abuse directed at him from thousands of Chinese swimming fans.