Inside No. 10

In the first in a series of interviews with all five living former cabinet secretaries, political journalist Sue Cameron talks to Lord Armstrong about the role of the most powerful civil servant in the land always at the Prime Minister's shoulder.

In the second in a series of interviews with all five living former Cabinet Secretaries, political journalist Sue Cameron talks to Lord Butler about the role of the most powerful civil servant in the land always at the Prime Minister's shoulder.

In the third in a series of interviews with all five living former Cabinet Secretaries, political journalist Sue Cameron talks to Lord Wilson about the role of the most powerful civil servant in the land always at the Prime Minister's shoulder.

In the fourth in a series of interviews with all five living former Cabinet Secretaries, political journalist Sue Cameron talks to Lord Turnbull about the role of the most powerful civil servant in the land always at the Prime Minister's shoulder.

In the last in a series of interviews with all five living former Cabinet Secretaries, political journalist Sue Cameron talks to Lord O'Donnell about the role of the most powerful civil servant in the land always at the Prime Minister's shoulder.