Scott Carson is not sure whether he was too nervous or too relaxed when England played Croatia in November. If he is honest, he struggles to make any sense of it at all. Should he have been a yard farther off his line? Could he have been quicker to move his body? Was it a failure of mind or technique?

“I look at it and I don’t know how I’ve done it, I don’t know why I’ve done it,” he said, candidly, of the shot from Niko Kranjcar that bounced off the sodden Wembley turf, past his left shoulder and into the gallery of English goalkeeping nightmares. “I’ll face a shot like that hundreds of times and I’ll throw my hat on it,” he added.

As Fabio Capello went back over the tape, he must have wondered how on earth it happened, too. And the new England manager will surely have concluded that only by throwing Carson back into the fray will he discover who is “England’s No 1”, a chant heard at various Barclays Premier League grounds although not sung anywhere with conviction in the past few years.

It cannot be Paul Robinson, given that he is not even good enough for Tottenham Hotspur at present and David James, for all his wonderful form with Portsmouth, is 38 in August. Ben Foster is untried and recuperating at Manchester United from a serious knee injury.

Robert Green? The position is so open to debate that Manuel Almunia has been mentioned with a straight face by Arsène Wenger, his club manager at Arsenal. The Arsenal goalkeeper, as English as paella, becomes a UK passport-holder by Christmas.

It is anyone’s guess what Capello – and Franco Tancredi, his goalkeeping coach - will do when they name their squad, never mind their team, but Carson is the man in possession and deserves another chance. He seeks to make no excuses for his eighth-minute horror at Wembley last year, but a defence barrister would offer plenty of mitigation.

Asked to guess Carson’s age and you would probably say mid-twenties. It feels as though he has been around for years because he has played for Leeds United and Liverpool as well as Sheffield Wednesday, Charlton Athletic and Aston Villa (all on loan).

But the man Steve McClaren threw into the bear-pit, behind a central defence that would have given Dino Zoff sleepless nights, was only 22, an adolescent in goalkeeping terms. “I’ve been all around the place, but I have only played 70 or 80 games in first-team football,” Carson said. “It may be two or three hundred before I can be everything I can be.”

Furthermore, he had made his senior debut only five days earlier in the insipid, pointless 1-0 victory over Austria. “If Steve McClaren had actually asked me if I was ready to play for my country, I would have looked in the eye and said, ‘Yes, pick me,’ ” Carson said. But he might also have added that the last fraught fixture in a doomed qualifying campaign was not the ideal time to be thrown in.

“I had an inkling that I might be in the team, but I didn’t say anything to anybody in case I’d got it wrong,” Carson said. “It was only on the morning of the game that Steve McClaren told me.

“Playing in a qualifier, it was an unbelievable feeling, hard to take. I trained the morning of the game and felt great. We were back in the hotel. I looked out of the window and it was absolutely pouring with rain. I thought, ‘Great, Sod’s law.’ ” So about the goal? “Coming off the Austria game, I was full of confidence,” Carson said. “Maybe too much, I really don’t know. People said it was nerves, but I didn’t really feel that way.

“I can’t remember the last time something like that happened to me. It wasn’t easy putting it out of my mind after a big night at Wembley with all my family in the stand, but there’s been nothing like it since.” The response of the man affectionately nicknamed Trigger by his England teammates after the dopey character in Only Fools and Horses, the BBC sitcom, has been hard graft on the training ground. Carson is not a convert to sports psychology.

He motivated himself after he was rejected by Newcastle United as a teenager and his best job prospect was at Sellafield nuclear power station, where most of his Cumbrian friends headed from school (although not his brother, Grant, a goalkeeper on the books of Carlisle United).

Eventually picked up by Leeds, he performed well enough for Rafael BenÍtez to make him a £1 million purchase three years ago. Liverpool’s needy American owners will be thrilled at the tenfold profit that they should make if Carson makes a permanent move to Villa at the end of the season.

Martin O’Neill, the Villa manager, has been a demanding boss, but Carson has enjoyed it that way. At his previous club, Charlton Athletic, he had enough shot-stopping to last him a lifetime. “Here, I’m much less busy, but the manager wants me to be more dominant in the box,” Carson said. “You’ve got to sweep up behind, command your area. To reach the very top, you need to be good at all these things.”

O’Neill has been impressed by Carson’s eagerness to improve and also the way he recovered after the match against Croatia. “I have been spoilt by playing in front of two of the best goalkeepers that ever lived, Pat Jennings and Peter Shilton, so I expect my keepers to be world-class,” O’Neill said. “That makes it tough for Scott, but I’m seeing the improvement.

“I think I said to him, half-jokingly, after Croatia that I remember Shilton making a big, big mistake in the ’73 World Cup qualifier against Poland. There were terrible recriminations, England not going to the World Cup and Sir Alf Ramsey leaving. Shilts went on to be the best goalkeeper in the world and I’ve told Scott if he has half his career, we’ll all be delighted.”

Capello was at Villa Park on Saturday and, with perfect timing, Carson saved a penalty against Blackburn Rovers. So is he England’s No 1? “I don’t know, I just want to get in the squad,” he said. Perhaps no one knows, not even the England manager a week before his first match against Switzerland.