O'Donnell's evidence was unprecedented. This appears to have been the first time that a serving head of the Civil Service has ever presented views in public and in real time on the political rules of the game concerning the resignation and appointment of the Prime Minister. O'Donnell himself called his appearance before the committee a very significant event. Though intended to clarify the position, his statement gave an interpretation that struck some Tory journalists as partisan. Undoubtedly for the best of motives, the Cabinet Secretary exposed himself to charges of political interference by his obvious keenness towards coalition government.

O'Donnell produced before the committee a preliminary chapter of the Cabinet Manual dealing with constitutional procedures following a general election. The manual rightly pointed out that the incumbent Prime Minister, Gordon Brown, would be entitled to remain in office if he failed to gain an overall parliamentary majority until he suffered defeat in the new House of Commons. 

But O'Donnell went further in his oral evidence. Not only would Brown have a right to remain in Downing Street if the coming general election produced no overall majority for a single party, it would be his responsibility to remain in post until it became clear which party or set of parties could form the new government. In other words, the incumbent Prime Minister was to remain in Downing Street as a "caretaker" while the different parties carried out a series of coalition talks on the Continental European model. Since the idea of copying European institutions would be unpopular with many, O'Donnell recommended copying New Zealand, a Commonwealth country which had abandoned first-past-the-post and become much like a multi-party, West European polity. The Cabinet Secretary announced this novel doctrine even though the Cabinet had not given its approval. Nor did it stem from the practice following earlier inconclusive elections.

In its studies of desirable procedures for governmental transitions, the Institute for Government gave two main reasons — both bogus — to support the Cabinet Secretary's proposals. The outgoing Prime Minister should remain in office while the rival parties hammered out an agreement, first, because the Queen would thereby escape the risk of being drawn into party politics, and second, because there needed to be governmental continuity. The incumbent needed to remain in place on a caretaker basis while coalition negotiations (which could be prolonged) ensued.