The senior police commander in charge of the operation that led to the death of Jean Charles de Menezes said yesterday it was "entirely feasible" that a similar tragedy could occur.
Deputy Assistant Commissioner John McDowell was speaking at the fourth day of the inquest, held at the Oval Cricket Ground, which heard that some of the undercover Special Branch officers trying to identify a fugitive suicide bomber while posted outside the home of Mr de Menezes in Scotia Road, Tulse Hill, south London, were not equipped with a photograph of the suspect.
Despite an order from Mr McDowell that the surveillance teams should be supported by officers from Scotland Yard's CO19 firearms unit to detain anyone leaving the Scotia Road apartment block, the inquest was told none of the marksmen were in place when Mr de Menezes, a Brazilian, left to go to work on the morning of his death. Only four of the six CO19 teams normally available in London were on duty because of annual leave.
The jury was also told that high quality pictures of Hussain Osman, who was one of the gang of four terrorists who tried – and failed– to explode bombs in London on 21 July, had been recovered from his rucksack but nobody had informed Mr McDowell of their existence.
Mr de Menezes, 27, was shot dead on a Northern line Tube train at Stockwell Tube station by two CO19 officers, who believed he had been identified as a suicide bomber and was about to detonate a device.
Mr McDowell, who at the time was a commander in the Yard's SO13 counter-terrorism unit and was leading the investigation into 7 July and 21 July attacks, was in charge of drawing up the strategy to isolate the Scotia Road address, where both Osman and Mr de Menezes lived.
Giving evidence via a video link, Mr McDowell said the Yard was "trying to catch up" in the early hours of 22 July as it faced the challenge of trying to catch the four bombers amid concerns that they might strike again.
But under cross-examination from Michael Mansfield QC, representing Mr de Menezes's family, the officer said the complex nature of police operations and the nature of the threat posed by terrorists meant a repetition of the fatal shooting was still possible.
Mr McDowell said: "I very much hope this will never happen again. But at the same time, with human beings, it is entirely feasible the same tragedy may occur again just with the way that circumstances sometimes unravel themselves."
Laying out a succession of alleged errors in the police strategy, Mr Mansfield accused Mr McDowell of taking his decisions in a "vacuum" without considering what could be realistically achieved by his officers.
The jury was told that the core of Mr McDowell's plan – that the surveillance team would be supported at Scotia Road by CO19 officers – was flawed because it would take too long for the firearms units to receive their weapons and briefing in the early hours of 22 July to allow them to arrive in good time.
In a series of tense exchanges with Mr Mansfield, it also emerged Mr McDowell was unaware that 21 Scotia Road was an apartment block rather than a single house, that high-quality photographs of the suicide bomber were available before 5am on 22 July and that some of the Special Branch team in Scotia Road were only shown a photocopied picture of the fugitive at a briefing and not given their own copy.
Putting it to Mr McDowell that these oversights contributed to the Stockwell shooting, Mr Mansfield said: "Do you accept that there were significant lapses of information and knowledge by you which resulted in a strategy being set in stone that was entirely inappropriate?"
Mr McDowell denied the claims put to him, saying his strategy was "fit for purpose".
The inquest continues.