Any areas of doubt relating to the appointment of the prime minister have also been cleared up during her reign. When David Cameron kissed hands at the Palace last month as Elizabeth's 12th prime minister, he might have been aware that it has been paradoxically the loyalist Conservative Party which, during the Queen's reign, has been the cause of constitutional uncertainty which has drawn her towards possible controversy. 

Before formal processes were put in place to choose a Tory leader, a suitable candidate was simply allowed to "emerge" from a band of frontrunners. When Anthony Eden and Harold Macmillan resigned on health grounds, respectively in 1957 and 1963, the Queen had to seek advice on whom she should summon to the Palace to invite to form a Government. In both cases, the obvious candidate, R. A. Butler, was passed over — in the later case, in favour of the apparently eccentric choice of Sir Alec Douglas-Home. 

To some contemporaneous commentators, it appeared that the Queen had been involved to an unacceptable degree in choosing her PM. The truth, however, was that she had acted completely within the bounds of her role by taking the advice of her first minister, Macmillan, who had advised her to send for Douglas-Home as the only individual around whom the party and government could unite. The confusion — and the scintilla of uncertainty that it raised about the monarch's role — was if anything the fault of the Tories, not the Queen's. 

Her instinct has always been to avoid anything that could be construed as partisan. Even her otherwise much-loved father, George VI, made the highly questionable decision to invite Neville Chamberlain on to the Buckingham Palace balcony on his return from Munich. A similar gesture by the Queen is inconceivable: she has kept all politicians at arm's length. Perhaps the nearest she has come to a comment on an important constitutional matter was during her Silver Jubilee celebrations, when, in a speech to both Houses of Parliament, she declared that while she understood nascent regional loyalties, she could not forget that she was crowned Queen of the United Kingdom, of Scotland, Wales and Northern Ireland, as well as England. This was seen at the time as the Queen taking a position on devolutionary plans. Whether or not this was so, she has accepted and adapted to devolution. 

Perhaps only when she is gone will her silent strengths become clear and appreciated. Her successor's style is almost certain to throw them into sharp relief.