Northern Ireland Secretary Shaun Woodward has insisted that handing over criminal justice powers to the province was an "essential" part of devolution.
Addressing the Labour party autumn conference for the first time in his new role yesterday, he said the St Andrews Agreement had clearly set out what must be done.
Mr Woodward, who famously defected to Labour from the Conservatives eight years ago, also insisted PM Gordon Brown was as committed to Ulster as Tony Blair.
He told delegates at Bournemouth: "Conference, we still have an important task to complete devolving policing and criminal justice.
"And with Paul Goggins and Jeff Rooker, ministers of state, we will work to that end.
"The St Andrews Agreement was clear - not an a la carte menu for devolution.
"The second, completing stage is as vital as the first. It must be done... because it is the right thing.
"When Gordon became PM, he was as clear as his predecessor of the importance of completing our work."
Mr Woodward praised the key players in the peace process and vowed to complete it in a bid to deal with the past.
He told party members that the life of a child born in Belfast today was very different to one born in 1972 but said it illustrated how government can make a real difference.
But he insisted despite the symbolic meetings that have taken place over recent times, including Ian Paisley welcoming Irish President Mary McAleese to Belfast, that the past must not be forgotten.
He added: "Indeed it should never be forgotten - too many have given too much.
"The history of Northern Ireland has indeed begun a new chapter, perhaps even a new story altogether.
"So conference take pride and heart from Northern Ireland. Justice can rise up, hope and history have rhymed."