asked Her Majesty's Government:

Whether they will ensure that, apart from exceptional circumstances requiring immediate action when it is proposed to commit the United Kingdom to direct participation in any war, international armed conflict or international peacekeeping activity, they will not deploy the Armed Forces without the advice and consent of each House of Parliament. [HL2068]

As I said to the House on 7 February,

“the Government addressed this point in the House of Commons on 8 January. The position was also made clear in the Government's response to this House's Constitution Committee's report Waging War: Parliament's Role and Responsibility. The Government continue to listen to views about prerogative powers to deploy the Armed Forces and to keep their policies under review”.—[Official Report, 7/2/07, col. 705.]

I also said:

“Everyone accepts that it is inconceivable in the current climate that any Government would ever go to war without first having the support of Parliament”.

There is, however, no convention about how or when that should happen and what the circumstances would be.