Parliamentary Private Secretary to the Prime Minister Bonar Law's Parliamentary Private Secretary, J.C.C. Davidson acted in effect as his Chief of Staff. Margaret Thatcher's downfall from the Conservative Party leadership in 1990 is attributed by many to the actions of her Parliamentary Private Secretary, Peter Morrison, in failing accurately to count votes amongst Conservative backbenchers. Some Parliamentary Private Secretaries to the Prime Minister go on to hold higher office; Lord Dunglass served as Parliamentary Private Secretary under Neville Chamberlain and later went on to serve as Prime Minister in his own right. There can be multiple Parliamentary Private Secretaries to the Prime Minister at a given time.
Acting prime minister to an outgoing Prime Minister following an electoral defeat, and who by convention does not implement new policies or an interim Prime Minister who is appointed to perform a similar role to a caretaker Prime Minister, but who is typically not a Prime Minister at the time of being appointed. Within a Commonwealth nation, the office of Acting Prime Minister, like that of Prime Minister is found only in convention, and is not legislated. The Department of Prime Minister and Cabinet, or an equivalent ministry, drafts, reviews and publishes any formal conventions (though these are expressly non binding in a