Assassin

[rebbonk]

David Cameron is making a speech in Edinburgh when suddenly a man raises a rifle and shoots three times from only 10 yards away, but misses.
Security personnel and police chase the man across town and eventually capture him. On interrogation at a local police station, he states his profession as 'marksman'.

"Just a moment," says the interrogating officer. "You miss the Prime Minister three times from 10 yards away and now you try to tell us you're a marksman?"

"Well, I am a marksman," says the potential assassin,

Spoiler:

"but you try standing there with a rifle and dozens of people shoving you, all yelling 'Shoot! For God's sake shoot!'"