Exhausted to the point of delirium, battered swimmer David Davies had to be carried off to an ambulance after earning the most courageous medal of any British athlete at these Olympics.

Then, just when he should have been celebrating his hard-fought silver in the 10km open water marathon, the aggression out on the Shunyi rowing lake spilled over onto dry land as Davies got involved in a row with a Chinese official and doused her with a bottle of water.

Maybe this unseemly incident just represented frustration setting in for the Welshman as the realisation dawned that he would always have to live with the fact he'd just blown the opportunity of a lifetime to win gold.

Taking offence at being man-handled by the aggressive official trying to steer him to the medal ceremony, Davies protested "Will you shut up please!" and when the hassling continued, he chucked the water at her.

What a pity the episode should cloud what earlier had been an epic effort from Davies. With 800 metres of the 110-minute slog left, the 1500m pool specialist, who had survived kicks in the face by more streetwise opponents, struck for home and appeared to have left his tormentors for dead, only to veer calamitously off course.

Realising his mistake, he tried to correct - but actually over-compensated, allowing the Dutchman Maarten van der Weijden to sneak in.

The Welshman was only a couple of body lengths behind by the finish but he could not prevent one of the more extraordinary champions being crowned as Van der Weijden, who won by 1.5sec in 1hr 51min 51.6sec, had won a harder fight than this before. Five years ago he beat leukaemia to begin a Lance Armstrong-like comeback.

"At the end I didn't know what was going on, I was delirious and my head was spinning, I just wanted it so bad," said Davies. "It was all a bit of a blur and to go off on the stretcher was a bit mad. Still, I've got something to show for it."

There was real concern for the 27-year-old from Barry as medics swarmed around while he lay prostrate at the side of the lake. And there was widespread relief when his enthusiastic British supporters in the pouring rain, including double gold medallist Rebecca Adlington, discovered he was physically okay after being treated in the ambulance. Then it was time to face the harsh realities of his agonising near-miss.

"I know I made a lot of mistakes," conceded Davies, after adding silver to the bronze he won in the 1500m in Athens four years ago. "But I've only ever had three races at this event."

He was the best man here but he may have been the least streetwise. His pool pedigree - he was sixth in last week's 1500m final - put him a class apart and even when his strongest opponents clearly felt the only way to stop his smooth progress was to start trying the rough stuff, the Loughborough-based athlete wouldn't be deterred.

"They were swimming all over the top of me - I felt a bit violated to be honest," said Davies. "My goggles got hit, I had a foot in my mouth and got struck by elbows - but I did try to give back as much as I was getting."

Russian world champion Vladimir Dyatchin got disqualified while German soldier Thomas Lurz, the former world champ, repeatedly tried to intimidate Davies with rough stuff.

The maddening aspect for Davies was that, after taking all they could throw at him, he still managed to find clear water and surge some eight lengths clear before he started taking the wrong line.

"Maybe I'm just too nice a guy," he mused afterwards. "Perhaps I should go back home and start hanging around with the ruffians!"

With his water-chucking anger a few minutes later, perhaps he's already started taking the role of bad guy before Hyde Park and the Serpentine in 2012.

"I definitely want to do that one," he said. "Hopefully I'll have learned to swim in a straight line by then!"