In the coming election campaign he is sure to be questioned on the matter constantly. Even if he is successful on 7 May he will be taken less seriously on the international stage.
Any notion that there would be a “seamless” transition to a new leader in five years’ time is fanciful. Even the most charismatic leader needs some time to become identified in the public mind. He or she would need to be in place by the spring of 2019 by the latest.
After an election victory, speculation about his successor is likely to be incessant. It may be somewhat more cordial than the nastiness that ensued in the later years of Tony Blair’s premiership over Gordon Brown’s succession.
It will still not be conducive to good government at a time, perhaps, when important negotiations over Europe, in particular, are ongoing. What might have been in Mr Cameron’s mind was his place in history in terms of length of leadership.
By May 2020 he could not possibly have improved on Winston Churchill’s near 15 years or Mrs Thatcher’s near 16 years at the Conservative helm. All the more puzzling that he should have declared his hand unnecessarily at a time when the political fortunes of all parties are so fragile, and the destiny of his own so perilous.