The brutal beheading of a journalist in Iraq by an Islamist terrorist believed to be from the UK has appalled Westminster, as elsewhere.
It has piled pressure onto the prime minister to recall MPs from their summer break to debate the crisis.
And he has returned from his latest holiday to coordinate the government's reaction.
At the moment, there is no sign parliament will be recalled to debate the issue but events are moving quickly and the prime minister may find the demands are irresistible.
