The 23-year-old Swansea Harrier earned this distinction by becoming first Briton home in the Virgin Money London Marathon on Sunday (April 23) in a time of 2 hours 14min 49sec on an astounding debut at the distance.

Okay - he didn’t quite match up to the marathon debut made by Kenya’s world record holder Dennis Kimetto, who ran 2:04:16 in finishing second in the 2012 Berlin race. But then again, by the time Kimetto toed the line in the German capital he was already a world record holder over 25 kilometres thanks to his victory in the Big 25 Berlin race.

Griffiths arrived at his first marathon with a far humbler record and a far more modest expectation - which he proceeded to surpass in memorable fashion as he finished 13th. 

"I wasn't expecting this. This is all very new to me," Griffiths said. "The goal for me was to try and qualify for the Commonwealth Games team for Wales.

"To actually qualify for the World Championships in the summer is still sinking in. I was hoping to run under 2:16 but I knew it would be a big ask as it's my first marathon but I thought I'd give it a go."

After yesterday’s announcement by British Athletics, Griffiths told BBC Wales Sport: "It's crazy. You almost don't believe it's going to happen.

"It's such a jump from where you're at, so to make that jump is just surreal.

"To be back in London in the summer, competing in front of those crowds, it's going to be great."

Griffiths added that he intended to carry on with his current arrangement whereby he has no coach - a position that becomes less surprising when you consider that he is due to graduate in July with a Masters degree in Sports Coaching from Cardiff Metropolitan University.

Sensibly, Griffiths is steering well clear of making any predictions about whether he can win a world medal at the Championships due to be contested in the capital from August 4 until 13.

But his unexpected marathon debut flourish, and its immediate reward of an international appearance, brings to mind the similar rise to prominence of another club runner marathon virgin back in 1973 - Ian Thompson.

Thompson, then 24, debuted in the marathon only after being asked to make up the numbers for his club team, Luton United - the competition in question being the Amateur Athletic Association of England Marathon Championships.

Eight years before the first London Marathon, this effective trial for the 1974 Commonwealth Games that would start in Christchurch in New Zealand in January took place on the broad and largely straight avenues of Harlow New Town.

Although he had never previously raced more than 10 miles competitively, Thompson - then ranked no higher than 90^th in Britain’s 5,000 metres rankings - beat a field which included the then Commonwealth champion Ron Hill in a time of 2:12:40, the fastest time that had been recorded for a marathon debut.

Three months later in Christchurch he took Hill’s title, beating the defending champion and also Derek Clayton of Australia, the world's fastest marathoner. Thompson finished more two minutes clear in a time was 2:09:12 - the fastest  ever run in a championship to that point, a British record and only 39 seconds off Clayton’s world record of 2:08:34.

He followed up by winning the Athens Marathon over the classic route. And then, in tremendous heat, he took the European title on the cobblestone course in Rome, finishing in 2:13:19, a minute-and-a-half clear of a field that included eventual bronze medallist Gaston Roelants of Belgium, the former European and Olympic 3,000m steeplechase champion and double world record holder.

In that annus mirabilis of 1974, Thompson was quoted as saying: "I prefer to remain in blissful ignorance of the opposition. That way I’m not frightened by anyone’s reputation."

Jack Foster, the naturalised New Zealander - ironically he was born in Liverpool, not so far from Thompson’s native Birkenhead - who took silver behind the Briton at the 1974 Commonwealths at the age of 41, asked afterwards: "What’s he going to do when he gets a bit of experience?"

But as things turned out, experience proved increasingly bitter for the novice champion. Having taken a year off, Thompson was obliged to prove his form ahead of the 1976 Montreal Olympics at the trial race in Rotherham, where selectors had decided the first three home would be chosen for the trip.

Two weeks before the trail Thompson was stricken by a virus. "I didn’t have the nous to drop out like a lot of runners would now," he told me 13 years later as he prepared for the 1989 London Marathon at the age of 39.

He finished seventh, sparking not exactly the kind of uproar that Sebastian Coe’s absence from the Olympic team created 12 years later, but certainly a respectable kerfuffle.

Frank Shorter, the 1972 Olympic champion, said he had feared Thompson more than anyone else in Montreal. The British Olympic Association threatened to hold an Extraordinary Meeting. And a Daily Mirror reader proposed the launch of an "Ian Thompson MUST go to Montreal" fund…

"Montreal was a big blow," Thompson recalled. "I still feel that I could have got a medal of some kind."

His star was waning. He failed to qualify for the 1978 European Championships, and although he won the Olympic trial race for the 1980 Moscow Olympics, he failed to finish there.

On the day we spoke he was preparing to start the London Marathon from the very back of the field before seeing how many tail-coated waiters, pancake tossers and serious runners he could pass.

It was his idea of fun as he looked ahead to the potentially serious competition of veterans racing that awaited him when he turned 40 later in the year.

"I’m a typical nutter runner," he said. "I’ve always put in more training than is good for me. And because I’m not a natural speed merchant I had to dig so deeply into my reserves to find that level of performance early in my career.

"But then it is very difficult for any athlete to stay at a peak. Two to three years is pretty good. Four to five is brilliant. Only very few, such as Coe, can stay at the top for 10 years.

"When I started I ran more or less like an African would, without a definite plan. But marathons get harder the more you do."

Josh Griffiths - you have been warned. But maybe you have been a bit inspired too…