Just to put the record straight with reference to the Torrey Canyon incident, the initial briefing was to try to set light to the oil, rather than to try to sink the ship. Consequently, the ship was opened up a bit more (the bombs and rockets that hit), and the "petrol" (actually napalm) was dropped to miss the ship and attempt to set the oil alight (the "bombs" that missed). It failed mainly because the "advisers and taskers" didn't seem to know that the heavy oil actually floats just below the surface of the sea water, so the napalm only caused the sea to steam a lot.
The hardest part of the whole episode was the poor old boss trying to explain why the RAF had those "Vietnam Horror Bombs" and nobody had known. What the "press" didn't realise is that anybody who had fuel, a gelling agent and an ignition method could have the "Vietnam Horror Bomb".