London's Metropolitan Police Commissioner Sir Ian Blair refused to resign today in the wake of the verdict in the Jean Charles de Menezes case.
He expressed his "deep regret" for the "tragedy" of the innocent Brazilian's death, but he insisted it was an "isolated breach" under "extraordinary circumstances" and gave his backing for all officers involved in counter-terrorism.
Sir Ian said he would now consider whether of the Met's procedures needed to be altered.
Speaking outside the Old Bailey, he said: "As the judge noted, the failures alleged were not sustained or repeated. This case thus provides no evidence at all of systematic failure by the Metropolitan Police.
"And I therefore intend to continue to lead the Met in its increasingly successful efforts to reduce crime and deter and disrupt terrorist activities in London and elsewhere in the United Kingdom."
The Liberal Democrats earlier called for the Sir Ian's resignation. Lib Dem home affairs spokesman Nick Clegg said: "This guilty verdict makes it unavoidable that Ian Blair should take responsibility on behalf of his whole organisation and resign."
Mr Clegg said: "The simple priority today is to show that we have a police force in London which is prepared to accept full responsibility for its actions."
The family of Jean Charles de Menezes pledged today that they would not rest in their fight for justice and said they were awaiting a "full and thorough" inquest.
Speaking after the court hearing, Erionaldo da Silva, speaking on behalf of the family, told reporters: "Today is emotional for us, here in London... "I have spoken to Jean's mother, Maria, and she said nothing can bring Jean back, but she's at least pleased that the men and the women of the jury have found the Metropolitan Police guilty of the charge...
"We remain determined to ensure that the full truth about Jean's death is made public and those responsible for his death are held accountable in a court of law.
"We are now awaiting a full and thorough inquest, where we as a family will finally be able to participate and seek answers to all our questions. "We will not rest in our fight for justice."