He was followed by another officer as he boarded a Number 2 bus for the 15-minute journey to Stockwell station, while members of the security services tried to confirm he was the man they were after.

Scotland Yard will not confirm the chain of command for the operation, which they say is a key part of the independent inquiry into the shooting.

But it is known that policing for special events and incidents in London is co-ordinated from a command room containing "gold" and "silver" commanders, with "bronze" commanders "on the ground".

Cressida Dick, a commander in the Met's Specialist Crime Directorate, is thought to have had a key role.

Police will also not confirm whether officers were instructed to prevent Mr Menezes boarding the bus or entering the station.

Initial witness reports suggested he was wearing a thick, padded jacket, despite the warm weather. And police said soon after the shooting that the dead man's clothing and behaviour had added to their suspicions.

Yet documents and photographs of the scene suggest he was wearing a blue denim jacket or shirt.