By Neil Silver, PA Sport

Padraig Harrington believes golfers will "go nuts" if they have to worry about whether or not they are filling out the correct scorecard.

The Irishman was speaking as the great scorecard debate continued to rage at Royal St George's, following Saturday's disqualification of Mark Roe - who was in Open contention - and Jesper Parnevik, who had filled out the wrong cards in the third round.

Harrington knows more than most how Roe will be feeling. He was five shots clear in the 2000 B&H International when it was discovered that he had not signed his first-round scorecard, and he was disqualified on the Sunday morning when he looked destined to win.

"I feel great sympathy for Mark - he could have won the Open," said Harrington, who ended the tournament on seven over par.

"You could see his reaction and it is not like he did anything wrong - it would be far worse if he'd played bad golf, but an error like that is out of scope; it is chance, luck, fate, or whatever you want to call it.

"It is not his fault it happened, it just happened, and it is not an issue where you apportion blame. It's an easy mistake. If an accident happens, it happens; it has happened many times and been spotted and I am sure it has happened many times and not been spotted.

"I don't think it was avoidable - you cannot legislate for something like this. You would be nit-picking if you went around your whole life worrying about little details; you just can't do that or you'd have no life. Can you imagine if every time you had to start worrying about those things? You'd go nuts.

"It is a little thing in the context of every day we play golf, and the pressure you'd be putting yourself under if you were worrying about little things would make you ruin your life. This game is stressful enough worrying about your golf swing and other things without getting into the bitty details, it is a pure accident."

However Harrington understands why the rules of golf had to be adhered to and that Roe and Parnevik had to be disqualified for their error. He also explained how after his experience he took steps to avoid it happening again.

"Under R&A golfing rules disqualification is not too harsh, but under professional golfing rules there is a certain call to move away from it," he said. "The R&A are responsible for golf all around the world and this tournament has to be run in the same way.

"When it happened to me I sat down afterwards and had a little think about how it could possibly happen again. Somebody said to me it wouldn't happen again, but I said it certainly could happen again.

"What happened with me was that there were two signatures, but neither of them was mine, so I decided that in future I would sign the top of my card across my name - as well as at the bottom - so that I know it is my card.

"I've no idea whose card I was given before each round this week, if it was mine or an opponent's, but I know I put the right card in at the end. You check it afterwards, that's the idea - if you worried about it during the round when you had everything else to think about it would drive you insane.

"I have a policy now and maybe everybody else should use that policy, but that's my policy so I don't have to worry. I have tried to cover all options for the future but I am not saying it won't happen again - the silliest things happen in golf all the time."

Harrington advised Roe not to be too hard on himself following the costly mishap. He added: "Mark must not second guess himself, it was an accident and he can't apportion any blame on himself - he must leave it at that and continue playing, and he is playing well."

Meanwhile it was the end of a bad week for Northern Ireland's Darren Clarke, who finished 13 over par. As he rushed to get a car away to take him away from the course he said: "I am playing rubbish, simple as that."