This is one of a string of what were once mining villages at the head of the Dulais River in the valley between Swansea and Neath. The village is so called because Evan Evans Bevan, a South Wales industrialist, named a mine Seven Sisters on account of the fact that he had... seven sisters.
The club reached the last eight in 1985 when they had a famous victory over Maesteg, before losing to Bridgend 14-6.
Their quarter-final yesterday was not so much David and Goliath as Dai and Dai. Garndiffaith, another defunct mining village in east Gwent, are, like Seven Sisters, in Division Four of the Welsh leagues. They had already met twice this season, with Seven Sisters winning on both occasions, 20- 18 and 17-16.
Their task in the cup was made considerably easier by an act of lunacy by Richie Cox, the Garndiffaith lock. He had already received a yellow card for putting the boot in and, when he did so again in the 18th minute, Clayton Thomas, the international referee, had no option but to send him off. To make matters worse, Cox remonstrated with the crowd as he left the pitch.
Seven Sisters - playing into a wind which seemed to come from the Arctic, as the surrounding hills were covered with snow - led 3-0 at half-time, thanks to a magnificent defence and a penalty by full-back Andrew James. After the interval, Seven Sisters scored five tries against their depleted opponents with James, a former Wales youth cap, having a memorable match. He scored one of the tries, converted four and added a second penalty for a contribution of 19 points. Next season, he is expected to join Leeds, where Phil Davies, a son of Seven Sisters and the former Llanelli and Wales No 8, is director of rugby.
The last mine in the area closed in 1989, since when, according to David Watts, the club secretary, "the main pastime has been unemployment".
Last week, Seven Sistersentertained Tumble in Division Four. At pounds 2.50 a ticket, the gate receipts were pounds 105. Yesterday a couple of thousand spectators stood on the touch line, paying pounds 5 a head, so the treasurer was rubbing his hands. Seven Sisters' answer to the call of professionalism was to pay a win bonus of pounds 40 on top of - nothing. If the players lose they do not receive a penny; if they draw, likewise. And that incentive applies only to league. "The cup is different," Watts said. "They will get a couple of pints."
The only blot on a red-letter day for Seven Sisters was that near the end they lost Mark Chilcott, their captain, who was carried off by stretcher with a leg injury. But not even that setback could stem the flow of beer in the same clubhouse.
This marvellous occasion was a welcome diversion for Dennis Gethin, the new secretary of the Welsh Rugby Union. No sooner had he taken over one of the most powerful jobs in Welsh rugby than the national team was wiped out by France at Wembley. A Seven Sisters boy, Gethin was a useful full- back, playing for Neath grammar school and Cambridge University. Yesterday he was back at his old stamping-ground.
Seven Sisters: A James; D Francis, K Thomas, A Hughes, K Lewis; H Evans, L Paget; P Elkins, L Griffiths, I Beech, Jeff Davies, James Davies, M Wareham, M Chilcott (capt), A Thomas.
Garndiffaith: D Rudge; R Morgan, P Taylor, C James, S Cross; M James, I Jenkins; M Spencer, R Thorne, J Lilley, G Morgan, R Cox, S Crosby (capt), D Evans, G Kirkup
Referee: C Thomas (WRU)