Cameron is one of the principal supporters of prohibition. His irresponsible and hypocritical drugs policy, along with his co-conspirators in the US is what creates the climate in which Indonesia implements such harsh and inhuman punishments.
Of course it's true that cocaine can lead to death and misery but in reality it's no more dangerous or harmful than alcohol. It is prohibition that creates all the most severe harms around cocaine and leads to the situation where this poor woman has apparently been coerced into acting as a drugs mule.
Cameron must bear his share of responsibility for the Indonesian death sentence. If Lindsay Sandiford faces a firing squad, then Cameron and Obama will be members of it. Make no mistake, they will be pulling their triggers. They will be to blame.