Graham Davis was on honeymoon in Egypt when he realised he had to lose weight.

“I saw a picture of myself in an XL football shirt with it clinging to my belly and I thought, ‘I don’t want to have to go up to XXL’,” he said.

That was five years ago and it was the start of a journey that has seen Graham – known to everyone as Gray – who stands 5ft 6in, drop from 18st to close to his target weight of 11st.

“The wife and I were both on the big side when we got together in 2009,” admitted father-of-two Gray, “but it wasn’t something that we got to grips with straight away.”

These days 37-year-old Gray is a committed member of Gloucester Athletics Club and is preparing to run his third marathon – the Gloucester Marathon – on Sunday 6th August, while his wife Emmi is a committed “healthy eater”.

After returning from his honeymoon Gray signed up for the NHS programme ‘Couch to 5K’ which pretty much does what it says on the tin.

“I used to go to the gym and run on the treadmill and that was where my running career was born,” Gray said.

However, the gym wasn’t really for Gray and by April he was competing in his first road race.

Gray takes up the story. “The race was on 1st April and it might as well have some kind of wind-up. It was the Tredworth Road Race over 4.2 miles and I didn’t do very well.

“I enjoyed it but I did feel ‘done’ afterwards. It took me 46 minutes, 22 seconds. I ran the race again in 2015 and ran it in 33 minutes, 30 seconds – a vast difference!”

Undeterred Gray entered the 2013 Cheltenham Half Marathon six months later and completed in two hours, 37 minutes. Five weeks later he was running the Birmingham Half Marathon which took him four minutes longer.

In March 2014 he decided to run the Reading Half Marathon – primarily because that was the town of his favourite football club – but there were to be few cheers at the final whistle as he crossed the line in two hours 53 minutes.

A pattern was emerging and it wasn’t a good one – another half-marathon and on each occasion a slower time. Worse than that he actually collapsed 50 yards short of the finish at the Reading Half.

“I had to be carried over the line,” he said, “although I made sure my feet were still on the floor!”

Clearly, though, there was something wrong and Gray was honest enough to admit it was down to him.

“I wasn’t doing enough training, simple as that,” he said. “I was a fair weather trainer. If it was raining I didn’t go out.”

So Gray, who works as a van driver for Lakes Bathrooms in Tewkesbury, took his foot off the brake by joining Cheltenham-based club Almost Athletes.

“I needed some structure to my training,” he admitted, “and the Almost Athletes provided it. If it was raining you just had to get on with it.”

The proof of the pudding was in the eating as Gray “smashed” that year’s Cheltenham Half, recording a time of two hours, 12 minutes.

He’d really caught the running bug by now and he ran the London Marathon in April 2015, going round in four hours, 47 minutes, 55 seconds.

Gray has fond memories of his time with Almost Athletes – “They turned me from a slow, fat runner into a decent runner,” he said – but in April 2016 he decided the time was right to move so he joined Gloucester Athletics Club as a second claim runner.

“It was partly to cut down on the travel – we live in Hempsted in Gloucester – and partly because we’ve got two very small children – Oliver and Joshua – who I wanted to spend more time with.”

Last year he ran the Gloucester Marathon, but although he reached the halfway mark in two hours, 12 minutes he fell away badly in the second half of the race and trailed in with a disappointing time of five hours, 56 minutes.

“I hit the wall at 15-and-a-half miles in the Gloucester race,” he said. “In the London Marathon I didn’t hit the wall until 21 miles.”

Gray was concerned and went to see a doctor who ran some ferritin blood tests.

“My iron storage level was very low, particularly for a runner,” he said. “They gave me some tablets but still my levels weren’t up to what they should be.

“It turns out that the problem was that I was a regular blood donor – I gave blood every 12 weeks and have given 43 donations of blood over the years.

“My body wasn’t replenishing enough iron between donations so I was unknowingly depleting my irons stores. I’ve had to give up donating blood for the time being.”

He has already noticed a difference.

“I feel fitter and strong,” he said. “My target last year was to run four hours, 30 minutes, and this year my aim is to run four hours 15 to four hours 30.”

Gray also has another target at this year’s marathon, which also incorporates a half-marathon with both races starting at 8am and beginning and ending at Gloucester Quays.

“I want to be able to complete this marathon without stopping, walking or being sick at the end,” he said. “I’ve not managed it so far.”

If his hard work is anything to go by he should achieve both his goals this time around.

He has been taking part in an intensive 18-week training programme for this year’s city marathon and is counting down the days to the start of the big race.

He has come a long way over the years. “I was always a chubby kid at school,” he admitted, “but even if I’m not down to 11st for the marathon I want to be that weight when we go to Tenerife later in August.

“That will be a celebration of me running the marathon and our fifth wedding anniversary.

“I know I’ve come a long way because when I took the family to the Championship play-off final this year, my Reading shirts were all far too big for me. I had to borrow someone else’s for the day out at Wembley!”