In Cardiff last week, England's captain Andrew Strauss spoke of how his team had "created their own intensity" to snatch victory on the final day of a match that seemed to have been destined for a draw. Any hopes of a repeat performance in the second Test at Lord's, however, were shattered - quite literally - by an incident involving Matt Prior, a pane of glass and an injured female spectator.

There were other factors that contributed to the sedate finish, of course - not least the solidity of Sri Lanka's batting, with Tharanga Paranavitana once again displaying his adhesive qualities at the top of the order. But as Strauss admitted at the close of play, the embarrassment of the incident, and the knowledge that it could have been more serious, scuppered any hopes England might have had of replicating the focus that proved so irresistible in the first Test.

Prior, who made a century in England's first innings, was annoyed after being run out for 4 second-time around, as his side chased quick runs before declaring on 335 for 7, a lead of 342. But as he returned to the England dressing-room, he took off his kit in a manner that led, apparently accidentally, to the breaking of one of the windows overlooking the benches in front of the pavilion, and a small cut on the ankle for a female spectator sitting below.

The circumstances of the breakage, however, were shrouded in confusion. According to the original explanation from the ECB, Prior threw his batting gloves across the dressing-room towards his kit bag, but accidentally dislodged a row of bats that had been propped up in front of the window. Soon afterwards, however, the ECB admitted that there may have been some "misinformation", and a subsequent statement, citing Andy Flower, who had been present in the dressing-room, explained that Prior had placed his bat on the ledge by the window, but the handle had bounced off the wall into the pane.

As it happens, Strauss himself offered a third version of events when he spoke to the press after the match, when he said that Prior's bat had bounced off another bat into the window. Small discrepancies, maybe, but it all helped contribute to a ridiculous scenario whereby England's off-field behaviour was under more scrutiny than their on-field efforts to win the match.

Strauss's initial reaction to the incident, caught on Sky's cameras, was one of visible disapproval as he shook his head in disgust, and though he later conceded it was a genuine accident, he wasn't exactly pleased with what had gone on. "It's not a great situation really," he said. "I'm not going to be encouraging my players to be breaking windows in a hurry.

"We're always annoyed when we get out, especially when we get run out. But I don't think that was the reason the window broke," he added. "It was an unfortunate thing, and important that he apologised to the people down below - because it potentially could have been quite dangerous. But it wasn't something that was intentional, and we hope we won't see it again."

According to an eye-witness, the lady who suffered the injury was an MCC Associate member from Ireland, who was making her first visit to the pavilion. She was treated at the scene by the England doctor, and reportedly bore no grudge when Strauss accompanied Prior downstairs to issue the apology.

The incident revived memories of Ricky Ponting's fit of pique during the World Cup in Ahmedabad in March, when he broke a television screen following his run-out for 28 against Zimbabwe. Ponting's excuse was that he had thrown his groin protector into his kit-bag, only for it to bounce up into the corner of the screen. He received a reprimand from the ICC as a result, but as far as England are concerned, this case is closed already.

Nevertheless, the incident had the effect of cooling England's ardour as they set about fielding for the final 58 overs of the match, with Prior himself - usually a vocal presence behind the stumps - understandably subdued afterwards. Four years ago against India, he was caught in the centre of a similar row involving jelly beans, a trivial incident on the face of it, but one from which his reputation took years to recover. There's no suggestion that he will be similarly pilloried for this episode, but he would not be human if it wasn't on his mind.

"I think he felt pretty contrite about it," said Strauss. "I don't think he quite realised at the time that there were people below him. Then suddenly when it hit home and you think about what could happen it hits you pretty hard. He wanted to go down there and apologise - it was the right thing to do - and thankfully no one was seriously injured. I think they appreciated the fact that he apologised."

Andrew Miller is UK editor of ESPNcricinfo