In this Act “Leader of the Opposition” means, in relation to either House of Parliament, that Member of that House who is for the time being the Leader in that House of the party in opposition to Her Majesty’s Government having the greatest numerical strength in the House of Commons; and “Chief Opposition Whip” means, in relation to either House of Parliament, the person for the time being nominated as such by the Leader of the Opposition in that House; and “Assistant Opposition Whip”, in relation to the House of Commons, means a person for the time being nominated as such, and to be paid as such, by the Leader of the Opposition in the House of Commons.

If any doubt arises as to which is or was at any material time the party in opposition to Her Majesty’s Government having the greatest numerical strength in the House of Commons, or as to who is or was at any material time the leader in that House of such a party, the question shall be decided for the purposes of this Act by the Speaker of the House of Commons, and his decision, certified in writing under his hand, shall be final and conclusive.

If any doubt arises as to who is or was at any material time the Leader in the House of Lords of the said party, the question shall be decided for the purposes of this Act by the Lord Chancellor, and his decision, certified in writing under his hand, shall be final and conclusive.