Halfpenny is full value as Blues kick on

London Irish 15 Cardiff Blues 22

Leigh Halfpenny kicks a penalty for the Blues against Irish (Getty Images)

Cardiff Blues sustained their pursuit of a Heineken Cup quarter-final place with an archetypal cup display, short on romance but long on hard work and perspiration. They remain neck and neck with Edinburgh at the head of Pool Two and another English club has left the competition.

London Irish can still do the Blues a favour by winning at Edinburgh next weekend, but the Welsh region have home advantage against Racing Métro and should not trip up. If Leigh Halfpenny, who earned them a losing bonus point at Murrayfield with a long-range penalty which could yet decide the pool, sustains his kicking form, the Parisians could be in for a long afternoon.

Halfpenny was entrusted with all the kicking duties ahead of Dan Parks and he fully justified the trust of his coaches. Had the assistant referees not decided that his second effort passed over the top of an upright, he would have had a 100 per cent return.

Cardiff deserved their win for their second-half display, during which they scored the game's only try and turned the line-out to their advantage. But it was a passionless affair. The Irish have more important things on their mind, such as the return of enough injured players to sustain their pursuit of an Aviva Premiership play-off place, and yesterday's selection included yet another member of their productive academy, David Sisi, an 18-year-old flanker who found himself head-to-head with Sam Warburton, the Wales captain.

"When you put out youngsters, you take the error count that comes with the selection," said Toby Booth, the Exiles director of rugby. "It's all part of their evolution and players like Sisi and Alex Gray will have learned a massive amount. We're very disappointed with the outcome of this campaign but we'll be better for the experience too."

Warburton was the try-scorer, early in the second half, appearing in support of a rasping break by Casey Laulala which carried him past Gray and Delon Armitage, though there appeared to be a Blues knock-on early in the build-up. The missed tackle was the only blot on Armitage's afternoon; the full-back put in a disciplined effort and kicked a penalty which nearly matched Halfpenny's first for length.

But the home backs seldom threatened. Darren Allinson enjoyed a good first half from scrum-half against his former employers but thereafter slightly over-played his hand. In 160 minutes of cup rugby against the Blues this season, the Irish have kicked 11 penalties and scored not one try. Three kicks by Adrian Jarvis gave them a 9-6 half-time lead. It might have been different had the Blues' Michael Paterson possessed the pace to finish a break created by Paul Tito from a turnover, but neither side had a player capable of breaking the defensive mould which hung over the game.

The Blues do not expect Jamie Roberts back next Sunday, to bring his physicality to bear. The Wales centre is taking longer to recover than expected from a knee injury suffered before Christmas, which will be a concern to the national-team management as the Six Nations creeps nearer. In his place, Gavin Henson made his third Blues start, having played twice at full-back. Every now and then came echoes of his best form.

"Gavin wants to be involved closer to the ball and he looked more comfortable than he did against the Ospreys," said Gareth Baber, the Blues' backs coach. "You saw a couple of little bits of class, a pass, a half-break – he has that vision, that skill level that you want involved as much as possible."

London Irish D Armitage; T Ojo, J Spratt, S Hape (S Shingler, 72), A Thompstone (T Homer, 72); A Jarvis, D Allinson; C Dermody (capt; A Corbisiero, 58), D Paice (J Buckland, 36), F Rautenbach (P Ion, 50), N Kennedy (R Casey, 76), M Garvey, B Evans, A Gray, D Sisi.

Cardiff Blues L Halfpenny; A Cuthbert, C Laulala, G Henson, C Czekaj (R Mustoe, 58); D Parks, L Williams (R Rees, 58); G Jenkins, T Thomas (R Tyrell, 63), T Filise (S Andrews, 50), B Davies, P Tito (capt; M Molitika, 72), M Paterson, X Rush, S Warburton.

Referee N Paterson (Scotland).

London Irish

Pens: Jarvis 4, Armitage

Cardiff Blues

Try: Warburton

Con: Halfpenny

Pens: Halfpenny 5