Jack Leach has described his run-out of Kusal Mendis on the fourth afternoon in Colombo as "the best moment" of his career to date.

Leach finished the series as England's equal-leading wicket-taker - he and Moeen Ali both claimed 18 - but it was the moment of brilliance in the field that gave him most pleasure.

That's probably understandable, too. Leach is a sound fielder but his direct hit from deep backward square leg - every bit of 50 metres from the stumps at the non-striker's end - was sensational.

Leach initially seemed just a little slow to reach the ball played towards him by Roshen Silva. But, alert to the situation and heeding his team-mates' calls to throw to the other end, Leach threw with admirable power and left Mendis well short with a direct hit.

It was an inspired piece of fielding, for sure, and drew comparison with Ben Stokes' run-out of Dimuth Karunaratne in Pallakele and the excellent work Keaton Jennings has been doing at short leg as key moments that have made the difference between the teams.

It was an important moment, too. Mendis, who had made 86, appeared to be batting Sri Lanka back into contention in the third Test, adding 102 for the fifth-wicket with Roshen. England were starting to look just a little flat and just a little nervous.

"I would love to say I've been working on those long-distance throws but I'd be lying," Leach admitted. "I've never done anything like that and actually think it was the best moment of my career so far.

"My towel at the back of my trousers wasn't quite in properly so, just before the ball came to me, I quickly threw it to the boundary. And then suddenly it looked like they were going to run two and I thought 'oh no! I've conceded two here and I shouldn't have done that.'

"So, I just launched it towards the stumps and thought 'that's going to hit' and luckily it did. So I was a bit lucky, really. It was a big moment."

Leach admitted he was close to exhaustion by the end of the game. The burden of bowling more overs than any other England bowler in the series, in back-to-back Tests and brutally hot conditions, was starting to take its toll, so he confessed his primary emotion upon taking the final wicket was simply relief that he could return to the air-conditioned dressing room.

"I'm absolutely knackered," he said. "I thought it was hot during the first two Tests, but then I got to Colombo and was like 'maybe it wasn't that hot [before].' Because it turns out Colombo is proper sweaty.

"Sri Lanka pushed us all the way. After the tea break Joe Root threw me the ball and I had to get the body going again. So I was just happy to get that wicket and get off the pitch.

"It has tested me physically, definitely. None of the guys are used to this so it is even more special that we could put in good performances to get the win.

"At the moment I just don't want to play cricket ever again, I'm so tired. But I'll give it a couple of weeks and then I'll be keen to get back in the gym and work on some things that I feel I can get better at and get myself ready for the Caribbean if I'm picked."

He needn't worry about selection. His is certain to be in the tour party and has a decent chance of winning selection even if England play only two spinners in some games in the Caribbean. And, even though he stresses that "everyone contributed" to the team's success, he does accept he has had "a great trip".

"It is a huge thrill to come out here and take wickets on spinning tracks," he said. "There have been ups and downs, but to come out on top with a 3-0 result is amazing.

"It has been a great trip for me. I feel like I've learnt a lot through winning games, which is how you want it. But I also think I need to keep getting better so this tour will really help me.

"Everyone has contributed: Stokesy's run-out in Kandy and his spell of bowling here; Keaton's fielding at short leg. Little things have made a big difference. And the way the batters have played has been something special. Rooty asked us to be brave with the bat and we've done that. It's special result. I'm just glad to have been able to play my part and be involved."