Josh Griffiths’ astonishing journey from club runner to British marathon international in the space of a few days has been confirmed.

The Swansea Harrier was today officially named in the GB team for August’s World Championships in London after his blistering display in the London Marathon.

Griffiths started behind the elite field on his marathon debut but charged through to finish 13th – and first Brit – in a time of two hours 14 minutes 49 seconds.

The Ammanford runner, 23, said: “The goal for me was to try and run the Welsh standard for the Commonwealth Games of 2:16:00.

“Obviously that is the same time as the qualifier for the World Championships, but the overall goal was to get that time in.

“To come in the first two British athletes and qualify for the World Championships is just something that never crossed my mind at all – I can’t believe it.”

Griffiths with join Robbie Simpson and Olympian Callum Hawkins on the Tower Bridge start line on Sunday 6 August.

British Athletics Performance Director Neil Black said: “Josh stunned the world with his 13th place this past weekend.

“I expect all of these athletes to produce very competitive performances this summer, especially with the support of a home crowd behind them.”

Griffiths is self-coached and may continue that in the build-up to London.

He said: “I currently coach myself and given my result, I might just keep doing what I’m doing because it seems to be working.

“I just love the challenge of it, I love pushing yourself and seeing how far you can take yourself.”

Britain’s marathon great Paula Radcliffe also advised Griffiths not to make too many changes following his breakthrough.

She said: “I would not rush into getting a coach because whatever he is doing is working well.

“It can become a weight when you make a breakthrough, so he needs to keep working and build on this at championships. He does not need to put too much pressure on himself.”