London Irish 26 Wasps 14: Exiles capitalise on errors to draw sting from woeful Wasps

It wasn't the experimental law variations that perplexed Ian McGeechan, just the old-fashioned fall guy, namely the referee. Andrew Small, a New Zealander in London, failed to act on blatant obstruction by Peter Hewat on Joe Worsley after a kick had been charged down.

No disrespect to Mr Small, who consulted a touch judge – why? He was much further away from the action than the referee – but the suspicion is that Ray Charles would have spotted the offence, just as 50,000 supporters did at Twickenham.

"In the end we could have scored three tries," McGeechan lamented. "When your attacker is pulled back by the last defender it's obviously a strong argument for a penalty try. I don't know who made the decision, whether it was the touch judge or the referee, but the advice was wrong."

Had Worsley scored close to the posts it would have made it 26-21 and Wasps would have got a bonus point which may or may not be extremely important come the end of the season. "We came back well, scoring two good tries and we should have got a bonus point," McGeechan argued. "We have to make the most of the times when we have the whole squad together but we didn't do that. It was a substandard performance and we're all very disappointed."

Now the Wasps' director of rugby and the Lions coach to South Africa was getting to the heart of the matter for, the Worsley injustice or not, the defending champions of the Premiership were bewilderingly out of sorts.

Their handling was appalling and their famed blitz defence was often blitzed by a London Irish side that was far sharper and far more together. To cap it all, Wasps conceded two of the softest tries from lineouts. Lineouts? They used to be a Wasps' speciality.

It all went horribly wrong for them from the eighth minute when the Irish No8 Chris Hala'ufia – he's actually a Tongan recruited from Harlequins – almost comically helped himself to a try from close to the Wasps' line. Even when Hala'ufia was sent to the sin bin for an ugly trip of Eoin Reddan, Wasps couldn't get their act together and with Hewat landing a couple of penalties the Irish had opened up a 13-0 lead by half-time.

That soon became 20-0 when Richard Thorpe took a flat catch at a lineout and sauntered clean through. Wasps were left looking at each other in a state of utter shock.

Perhaps the champions, who are so accustomed to winning big finals at Twickenham, a ground which has become almost their second home, were too complacent but many of their leading players didn't perform. Tom Rees and Reddan scored tries in the final quarter but they were never going to close the gap.

In key conflicts Mike Catt, who has become the Irish backs coach, looked better than Riki Flutey, who has been given a vote of confidence by Martin Johnson's new England and as for Hewat versus Mark van Gisbergen there was only one winner.

Wasps, of course, have Danny Cipriani to return to stand-off before Christmas but then here Catt had to come in for Shane Geraghty, who had turned an ankle, and the Irish were also without their influential lock Bob Casey who broke a wrist playing in a friendly against Munster.

Toby Booth, who used to be the forwards coach but has succeeded Brian Smith – Johnson has recruited him to the England cause – as the top Irish wolfhound at the Madejski, said: "If we had been more clinical we could have been further in front. Wasps came back at us and we expected that from them so to show the mentality to shut them out was fantastic. We're trying to get tougher in terms of our mindset and to deny them a bonus point was very pleasing. That was as encouraging a display as we could have asked for at this stage of the season."

London Irish: Tries Hala'ufia, Thorpe; Conversions Hewat 2 Penalties Hewat 4. Wasps: Tries Rees, Reddan; Conversions Van Gisbergen, Staunton.

London Irish: P Hewat; T Ojo, D Armitage, S Mapusua, S Tagicakibau; M Catt (capt) (E Hickey, 65); P Hodgson (P Richards, 72); A Corbisiero (D Murphy, 48), D Coetzee (D Paice, 60), F Rautenbach (J Buckland, 60), N Kennedy, G Johnson, R Thorpe, C Hala'ufia, S Armitage.

Wasps: M van Gisbergen (L Mitchell, 69); P Sackey, D Waldouck, J Lewsey (J Staunton, 40), T Voyce; R Flutey, E Reddan; T Payne, R Ibanez (capt) R Webber, 68); P Barnard (P Vickery, 51), S Shaw, R Birkett (T Palmer, 51), J Worsley, J Haskell, T Rees.

Referee: A Small (London).