A 19-year-old who doctors said may never walk or talk, has splashed into the records book after becoming the first person to break a world record at Medway Park.

Billy Birchmore is now the fastest man with Down’s syndrome in the world at 100m backstroke after smashing the former best time set by a Mexican, Ricardo Herrera, by nearly two seconds.

He set the new record, of 1:17.52, at the Gillingham pool during the Beachfield Swimming Squad Summer Open Meet.

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Billy said: “It felt really great because I knew I could do it.”

He already held the European record and his new time has been verified by the Down Syndrome International Swimming Organisation (DSISO).

His father, Steve Birchmore, said: “It’s a great achievement because he’s really been trying for the last year or so, but he just couldn’t quite get there.

“It’s the end of the season for swimming so we didn’t really think he’d break it but when he did, and by such a margin, we were quite astounded.”

He added: “It’s an inspiration to us as well as other Down’s children.

“The scenario when Billy was born was that he may never walk or talk, and he’s testament that with a bit of determination you can get really far.”

Billy only started swimming when he was 11 and didn’t take part in his first competition until he was 13.

He swam at his first world championships five years ago, has broken several world junior records and holds eight European records.

His mother Jackie Birchmore said: “I’m so proud. He puts in a lot of hard work, it’s a lot of travelling about but something like this is worth it.

“He really enjoys doing it and it keeps him fit.”

Billy, who lives in Chislehurst, trains six times a week with either the Orpington Ojays or the Sharks of Mottingham, a club for people who suffer from physical, visual or learning disabilities.

As things stand, rules may prevent Billy from achieving his dream of a paralympic gold medal, for now.

Watch: Billy Birchmore on his record breaking swim

There is only one para-swimming category (S14) for intellectual impairments and learning disabilities, unlike physical impairments for which there are 10 categories depending on the severity.

People with Down Syndrome come under the S14 category despite also having physical impairments, so Billy and others like him, have to compete against people who may be fully able-bodied.

There is a growing movement within the para-sport world to create a separate category for those with Down Syndrome.

Mr Birchmore explained: “It’s politics unfortunately. People with Down Syndrome are the biggest group of disabled athletes.

“It’s a little bit galling, if you looked at the London Paralympics there were pictures of Down Syndrome people everywhere but there were very few entrants, I don’t know of one in swimming or athletics.”

The DSISO was created to provide swimmers with Down Syndrome the opportunity to swim at world level through its world championships held every two years.