If their agonising loss in Toulouse was unfortunate and their late defeat at Leicester somewhat careless, Bath's second-half collapse against London Irish was completely inexplicable.

Head coach Steve Meehan will seek answers from his players when they return for training this morning, having watched them throw away a 17-0 half-time lead against their fellow Guinness Premiership title-chasers.

They could have lost, too, as their second-half error-count not only let Irish back in the game but allowed them a genuine shot at victory.

Bath had looked completely comfortable at the break, playing some of their best rugby of the season to date during a glorious opening 40 minutes.

Stuart Hooper, Matt Banahan and Joe Maddock all scored tries as the hosts blew Irish away with a rampant and clinical display which underlined their status as the best attacking team in the Premiership.

But after the turnaround they were sloppy. They regularly coughed up possession, missed their tackles and failed to maintain the authority they had shown during the opening exchanges.

If Adam Thompstone's excellent try seven minutes after the restart was a warning, it was one Bath failed to heed as they conceded further tries to Seilala Mapusua and Topsy Ojo in a frantic second period.

"It wasn't the happiest afternoon for us – and my question to the players at full-time was, 'How did you turn a 17-0 half-time score into a 20-20 draw?'" said Meehan.

"On a couple of occasions, they went away from working together and worked individually, which didn't help, and from a defensive point of view we gave them some good opportunities.

"The first Irish try was a good try, there's no doubt, but the second and third should never have come about. At times we strolled through the game, thinking 'somebody will take care of it', so obviously we are disappointed by that."

Bath monopolised early territory and possession, and the only surprise about their opening try – scored by lock Hooper after Banahan had capitalised on Tom Homer's failure to deal with a Butch James up-and-under – was that it took 12 minutes to arrive.

Nine minutes later, they were celebrating again, Banahan scoring out wide after David Flatman's storming break had punched a hole in the Irish defence in front of the posts.

And Bath took what appeared to be an unassailable 17-0 lead shortly before the interval. James kicked possession away, only for Topsy Ojo to send an equally poor kick back up-field.

Irish No 8 Chris Hala'ufia briefly grabbed possession, but soon dropped the ball, allowing Alex Crockett to pick up and launch a counter-attack, with Maddock and Banahan swapping passes to allow the former to score.

Bath simply did not get started after the break, though, and Thompstone raced in from 45 metres to begin the fightback after Andy Beattie had been turned over just inside the visitors' half. A Shane Geraghty penalty after Banahan ran himself into trouble in his own 22 brought Irish back to within nine points – and as Bath failed to keep hold of the ball, the visitors nicked another try.

The powerful Mapusua was arguably helped by referee Chris White's inadvertent block on a Bath tackler, and he sauntered in to reduce the deficit to four points.

James gave Bath a seven-point cushion with a penalty – but the Irish onslaught continued and they had the final say when Ojo was inexplicably allowed the freedom of the Recreation Ground to add a third Irish try, leaving James, Eliota Fuimaono and Nick Abendanon grabbing at thin air as he scored a fine solo try.

Geraghty landed the simple conversion to draw Irish level at 20-20 – and that is how it remained.

"Irish are a very good rugby side and you can't go to sleep against them – so to allow them the space and the holes we did was criminal," said Meehan. "When you're in a competition like this – and a season as long as this – you're always going to have your highs and lows. So if a draw with London Irish, who are travelling near the top of the table, is a low then it's not such a bad season.

"But we can still be very disappointed with the way things went in the second half."

Bath: J Maddock; A Higgins (N Abendanon 66), A Crockett (capt), E Fuimaono (S Berne 71), M Banahan; B James, M Claassens (S Bemand 78); D Flatman (A Jarvis 59), P Dixon (R Hawkins 71), D Bell, J Harrison, S Hooper (P Short 66), A Beattie, J Fa'amatuainu, D Browne (J Scaysbrook 69).

Scorers: Tries – Hooper, Banahan, Maddock. Con – James. Pen – James.

London Irish: T Homer; T Ojo, E Seveali'i, S Mapusua, A Thompstone; S Geraghty, P Hodgson; C Dermody (A Corbisiero 80), J Buckland (D Coetzee 59), A Corbisiero (T Lea'aetoa 48), J Hudson, B Casey (capt; G Johnson 80), R Thorpe, S Armitage, C Hala'ufia (D Danaher 48). Reps not used: P Richards, A Lalanne, E Hickey.

Scorers: Tries – Thompstone, Mapusua, Ojo. Con – Geraghty. Pen – Geraghty.

Referee: C White. Att: 10,600.