Sir Hugh said:
"I accept the findings of the court, which have been reached following Mr Justice Sweeney's consideration of a long and complex chain of events stretching back over thirty years, including decisions made in the context of a delicate and, at times, turbulent peace process in Northern Ireland and the policing and judicial landscape that adapted in tandem with that process.
"It is a matter of great personal regret that a crucial oversight was made by a senior officer which resulted in erroneous information being sent to Mr Downey by the Northern Ireland Office and thus prejudicing the current indictment.
"As chief constable, I worked at the head of a team of very hardworking officers. While no organisation is immune from errors, it has become apparent recently that a very serious error was made in dealing with Mr Downey's case, which is a matter I regret very deeply. I am informed that the PSNI is making sure that their systems cannot allow such a grave error to happen again and they will refer themselves to the Northern Ireland Police Ombudsman for investigation.
"Nevertheless, my mind is first and foremost with the families affected by the actions of those who perpetrated the bomb in Hyde Park in 1982, whose dignity in their grief has always been impressive. If a force under my command has failed them, as it seems it did, then I apologise to them unreservedly."