They live two miles from each other in Jenkins's home town of Pontypridd and, although from rival clubs, often train together at Sardis Road. 'There's a rapport,' Moon said. 'We have a similar sense of humour. It's not false, it's not something that can be taught. It's just there. We share the burden. If I'm under pressure he'll take the responsibility and vice versa. We never point a finger at each other if things go wrong.'
So far things have gone very right. Jenkins, aged 22, has 20 caps; Moon, aged 26, has nine and on the field it is the Llanelli scrum-half who has his hands on the control panel. It can be argued that Robert Jones, the man he displaced, is a more refined, classical scrum-half (a better passer, perhaps a better kicker) but Moon, bigger, stronger, has brought other qualities to Wales. Apart from a huge appetite for work, he is a great standard-bearer and his enthusiasm, not just for the game but particularly for the Welsh game, infects the team. Nobody is closer, in physical and spiritual terms, to Llanelli's international back row.
The irony is that Rupert Henry St John Barker Moon, born in the heart of England, should find himself at the heart of the Welsh team; just as Dewi Morris, his opposite number, should prefer the Rose to the Dragon. 'I don't feel unusual about that,' Moon, who describes himself as a born-again Welshman, said. 'I've played all my senior rugby in Wales. There are no divided loyalties and I'm sure Dewi feels the same. He doesn't wear three feathers on his chest.'
This is Moon's first match against England and only the second time he has played at Twickenham. Four seasons ago, after joining Llanelli from Neath, he played in a club match at headquarters against the Harlequins. He has only once played against Morris, in an all-England affair between the Midlands and the North, which ended 19-19. However, they were in England squads together. 'Dewi is a good bloke who has stuck to his cause. I was very jealous of him going on the British Lions tour but he deserved it.'
Moon, born in Birmingham, played for Walsall at 16 before following his brother Richard (Henry Quentin Barker) to Abertillery. Then taking business studies in Wales, Moon captained England Students and played for England Under-21 and England B, the latter under the influence of the present Wales coach, Alan Davies. After joining Llanelli, Moon, who captained them to a League and Cup double last year, registered for Wales. It may not be the land of his fathers but as far as he is concerned that is a geographical blip.
'When I came to study in Wales,' he said, 'I found my seventh heaven. In England they train and play hard but it doesn't affect their lives like it does here. I've played rugby since I was five and I love to talk about the game. It means so much to people here and that makes me feel comfortable.' All but one member of his family, his sister Estelle who has played scrum-half for Wasps Ladies, will be at Twickenham. 'She can't handle it. She hides behind the sofa.'
After the defeat by Canada in Cardiff earlier this season, Alan Davies might have experienced the sort of emotions subsequently felt by John Toshack. 'Canada are no mugs and we picked up a lot of things from that match,' Moon said. 'We came back more streetwise and that was vital in the way we performed in the last quarter against Ireland. It's also important that we brought an element of enjoyment back . . . individuality and flair. We enjoy our rugby by scoring tries.
'I know we can score tries against England. I'm confident with the people around me. Our heads will be held high at Twickenham for the first time in a long while and I think they'll be worried about that. We are difficult to defend against. We don't always do the conventional.' Wales have had a month to prepare and Moon said: 'The longer we've been together the better the team spirit has become.'
According to Moon, a big factor in Wales's recovery is that the internecine rivalry between clubs, which has often been damaging to the national cause, has disappeared. 'That's a tremendous compliment to Alan Davies. In the squad, clubs just aren't mentioned. I know that when I play against Swansea, Garin Jenkins will be out to get me but I know that for Wales he'll be watching my back. I'm confident. That's brilliant. You're more inclined to put your head on the block for somebody you get on with than somebody you don't'
Against France, Moon was often the catalyst for the back-row moves that put Scott Quinnell on the offensive. The England back row are expected to be a different proposition. 'People said we had to fear the French back row but we let them worry about us. I know Rodders and Clarkey and they'll be thinking what can they do to stop Moony. Then there's Scott, a big strong boy, quick off the back, and they'll be wondering how to stop him. Don't forget Neil can run and we've got ball-carriers out wide. Scott came to Llanelli straight from youth rugby and he thought he was still playing youth rugby. He thought he could take on everybody. He's matured beyond his years.'
The same might be said of Moon. You cannot miss him. He is the one with the chat and no collar to his jersey. 'I have respect for our opponents. They've got experienced players capable of performing on the day. But when 15 Welshmen have a belief in themselves then others have to watch out.' The mention of 15 Welshmen came perfectly naturally.
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