In the Wales changing-room after the victory over England at Twickenham last month, one man moved into the centre of the room and started to sing. Given that country's love for singing, you would think it was a Welshman. In fact, it was a small Englishman with a big presence who was responsible. Hardly had Shaun Edwards, the part-time Wales defence coach, begun his party piece - Saturday Night at the Movies - than the rest joined in and soon the walls resounded to a good singsong.

“We have a club song at Wasps and we sing it as a celebration,” Edwards said. “It's a bit old school, I suppose, but I am a big believer in some of rugby's values, even in the professional age. You have got to celebrate victories.”

Victories are all that Edwards, 41, has known since he added the Wales job to his duties as head coach of London Wasps. At Wales, Edwards linked up again with Warren Gatland, the New Zealander, who had been a successful director of rugby at Wasps.

Three victories out of three in the RBS Six Nations Championship have led Wales to anoint Gatland and Edwards as the country's saviours for two reasons. First, under them, Wales have the appearance of a world-class team in the making. The second is that Edwards was let slip by the RFU, the dreaded English to many in Wales.

“When Wales approached me, the RFU had mentioned the possibility of my coaching the England Saxons,” Edwards said. “I was tempted, even though I would have had no involvement with the England team. I desperately want to be involved with the Lions next summer and wondered what effect taking the Saxons job would have. Because I did not accept the RFU's offer it was withdrawn, so I had no decision to make in the end. I probably would not have gone to Wales if Warren had not been coach.”

An insight into his coaching methods could be seen at a recent Wasps training session at their base in West London. He was wearing a tracksuit and holding a piece of paper. He looked at his list often. Then, suddenly, he moved to the touchline. “Frankly, I was not happy with training today, to say the least, so I took a step back and allowed Lawrence [Dallaglio] to take over because the players knew the training was atrocious,” Edwards said later. “Sometimes when that happens, you have to let the senior players sort it out.”

This, then, is Shaun Edwards the coach, the brooding man whose training sessions have a reputation for being purposeful, thoughtful and hard. This is the man who sets high standards for his players because he set them for himself - and met them.

Edwards, once voted the fourth best rugby league player of all time, has 33 winner's medals. He made 467 appearances for Wigan, including their eight consecutive Challenge Cup victories, from 1988-1995. He captained England's under-16 teams at rugby union and league. He has coached at Wasps since 2002, first under Nigel Melville, then Gatland and now Ian McGeechan, during which time Wasps have won six trophies, including the European Challenge Cup in 2003, the Heineken Cup in 2004 and 2007, as well as three Premiership titles.

He passed all his rugby league coaching exams within a few days of turning 18, the earliest age at which he was able to sit them, and having turned to union he has achieved up to the grade four level of coaching - one short of completion.

At Gatland's insistence, Wales's training sessions are rarely longer than 50 minutes, and often shorter. “What you are trying to do in training is replicate what you do in a game, without the injuries,” Edwards said. “Warren likes to make the training harder than the game so that when the game comes around it does not come as a shock. It is not exactly rocket science, is it?”

Stephen Jones, the Wales fly half, agreed that training is demanding, but rewarding as well. “Shaun's sessions are intense,” he said. “You are put under pressure. The way in which he puts things across is very clever and precise. Everything he talks about is relevant to the game on Saturday. It is not a matter of just ticking boxes. He hits you with facts. I am fully aware that he is the boss. I respect everything he says and I feel that if I had an issue I could easily go to him and ask him about it. He is not the 'it's my way or the highway' type of coach. He likes to be challenged.”

The most significant thing about Edwards, Ryan Jones, the Wales captain, said, is that “he never smiles”. The reputation was borne out at the 2007 Heineken Cup final, to which some Wasps supporters wore a T-shirt featuring Edwards's stony face and the words: “Smiling on the inside.”

Edwards's eyes widened when he heard Jones's comment. “My face is due to the fact I played 17 years of professional rugby in the Eighties and Nineties and I can assure you it wasn't the most hospitable place to be,” he said. “You get a few cracks around your head and you end up looking nothing like you did when you were a 16-year-old.”

So much for Edwards the coach. Now comes Edwards the person, a man as comfortable sitting in a jazz club with a glass of red wine as he is exploring the historic castle in Cardiff or admiring the Georgian architecture of Matt Dawson's house in West London. This is the Edwards who was an altar boy at St Mary's Catholic Church in Wigan and works in a soup kitchen two or three times a month and who, according to one man who knows him, is “touched with gold dust”.

This Edwards, Jack, his father, says, is “a very, very, very nice person. I know I shouldn't say this, but his friends would die for him. Mind you, he was a terrible loser as a child, terrible, terrible, terrible. When we played cricket, even when his stumps were shattered, he would storm off the pitch until I fetched him back.”

Edwards is a religious person who devours books on coaching and performance improvement as well as spiritual matters. The Edwardses are a close family and not one of Jack, Phyllis or Shaun has come to terms with the death in a car crash four years ago of Billy Joe, Shaun's much younger brother.

Here is what links two of the main men behind Wasps' success. As Dallaglio struggled to come to terms with the death of his sister in the Marchioness tragedy on the Thames in 1989, so has Edwards in adjusting to life without a younger brother. “Billy Joe still affects me,” he said. “I am intense when it comes to rugby, but I know now that it is not life and death. It is a game. If we lose a game I am not so devastated about it as I was before Billy Joe died.

“Lawrence and I are like mothers who have lost children. There is a bond between us because no one else can understand it. At big games I know Lawrence thinks of his sister and wants to do it for her and at big games I am the same. I want to do it for Billy Joe and to make people proud of me.”

At the Wasps training ground later that day Edwards bumped into Matt Hampson, the England Under-21 prop who dislocated his neck in a training session two years ago and is in a wheelchair. Hampson is writing an autobiography and had come to interview James Haskell, the Wasps and England back-row forward.

At the entrance to the club, Edwards looked warmly at Hampson, not saying anything. Then he leaned forward and kissed him on the top of the head. At that moment the two Edwardses were as one - Edwards the coach, the man wearing the tracksuit, and Edwards the caring, religious person, the humane man.