David Cameron has paid tribute to a young policeman murdered by dissident republicans as he vowed to play his part in fulfilling the plea of the officer's mother that his death not be in vain.
The Prime Minister branded the killing of 25-year-old Ronan Kerr in Omagh in April a "vile and cowardly act" and said tackling terrorism remained a top priority of his Government.
Mr Kerr, a Catholic officer and keen Gaelic games enthusiast, was targeted in an effort to frighten other nationalists from joining the new-look police service.
In an address to the Northern Ireland Assembly, Mr Cameron said the violent renegades opposed to the peace process had nothing to offer and together the people of Ireland would ensure they would never succeed.
"There are some things we must do together," he said of the relationship between the Assembly and his Government. "Like standing united against the threat of terrorism.
"The murder of Ronan Kerr in April was a vile and cowardly act. Yet it was one of an increasing number of attacks that have taken place over the past two years.
"These terrorists have no mandate. They offer nothing. And they will never succeed. The people of Ireland, North and South, who backed the 1998 Agreement with such overwhelming democratic majorities will ensure that."
In the wake of his death, Mr Kerr's mother Nuala urged other Catholics not to be put off joining the police service. Praising her courage, Mr Cameron said: "Who here could fail to have been moved by the dignity and words of Pc Kerr's mother, when she said: 'We were so proud of Ronan and all that he stood for. Don't let his death be in vain'.
"Tackling terrorism is a joint effort in which the Northern Ireland Executive has a crucial role to play. For our part the UK Government has made countering the terrorist threat here a top priority."
Mr Cameron said he had proved his commitment by making available almost £250 million extra funding to tackle the security threat in Northern Ireland.