Heads I know have been told that they will be sacked on the day after Ofsted if the report is bad.
They have been screamed at by inspectors, and in one case have been spat at by the chief inspector.
They have been subjected to a level of interrogation that is normally reserved for criminals.
As well as that, they have pressure from the governors, and the parent body (who can often be very reluctant to believe that 'their lovely little school' is NOT as perfect as the previous head led them to believe, and thus blame an incoming new head for a perceived 'decline'), and political pressure due to forced academisation. Oh, and the general demands of what can be a very lonely job...