§ Mr. Deakinsasked the Lord Privy Seal what advantages the Secretary of State for Foreign and Commonwealth Affairs derives from the exercise of the 257W functions under the Royal Prerogative which would not be available if those same functions were exercised under statutory authority.
§ Sir Ian GilmourThe conduct of foreign relations inevitably requires that certain discretinary powers be vested in Ministers, for example, in relation to the negotiation and conclusion of treaties.
Ministers are, of course, generally responsible to Parliament for the manner in which they exercise powers under the Royal Prerogative, and the practice known as the Ponsonby rule, whereby treaties concluded subject to ratification are laid before Parliament for a period of 21 sitting days before ratifcation ensures that, in the field of treaty-making, Parliament has full opportunity to consider, and if necessary debate, the substance of treaty commitments into which the Government of the day may propose to enter. The frequency of statements and debates in Parliament on foreign relations is illustrative of the extent to which parliamentary control is in fact exercised in this field.