George W Bush refused to answer the question.

David Cameron managed a puff or two while at Eton, allegedly. Bill Clinton famously didn't inhale. Ed Miliband said he was too "square" to try.

But now a question has arisen - did Danny Alexander experiment with the odd exotic cigarette in his younger days?

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The Chief Secretary to the Treasury was asked what was the craziest thing he had ever done. Having rejected dancing naked on a table and a threesome, he was asked if he had ever smoked pot.

His reply, delivered in apparently flustered tones, was: "Er, um, things that happened many years ago I'm not going to go into. No, I'm not going into things that happened many years - may have happened, may or may not have happened - many years ago."

Other politicians, Yvette Cooper, Jacqui Smith and Chukka Umunna, have admitted to smoking cannabis with some suggesting the idea of politicians having used soft drugs in their youth is not newsworthy any more.

Nonetheless, the question still appears to have the capacity to fluster even as seasoned a politician as the Highland MP.