How long will the ‘honeymoon period’ for the new prime minister last?

Since the Second World War, there have been eight new prime ministers who have taken over mid-term from another PM of the same party – they all experienced a bounce in the polls, but the size of that bounce has varied substantially, writes Kelly Beaver

Will the new prime minister get a political ‘honeymoon’ period (Dominic Lipinski/PA) (PA Wire)

As the Conservative leadership contest rolls on, Ipsos is tracking public attitudes towards the two candidates: Liz Truss and Rishi Sunak. Whatever the public are thinking, one near certainty is that once one of them has become prime minister in a few weeks’ time, they – and their government - will most likely benefit from some kind of a “honeymoon” period when they will get a boost in their poll ratings.

Since the Second World War, there have been eight new prime ministers who have taken over mid-term from another prime minister of the same party, six Conservative and two Labour. We have looked at their poll ratings (using the Ipsos or MORI polls back to 1979. Every one of those eight prime ministers witnessed a “bounce” in the polls: their average net satisfaction rating for the way they were doing their job in the three months after they took over was higher than their predecessor’s average in their last three months; and average satisfaction with the government also rose every time.

The size of the bounce, however, does vary: John Major got a +70 net improvement when he replaced Margaret Thatcher, a 35 per cent “swing” (i.e., the equivalent of 35 people in 100 switching from dissatisfied to satisfied), but Harold Macmillan got only a +5 improvement when he took over from Anthony Eden. Most recently, when Boris Johnson replaced Theresa May, satisfaction with the prime minister rose a net +31, but satisfaction with the government rose only a net +14.