AS recorded in Plutarch’s Life of Julius Caesar, Pompeia, the second wife of the ambitious leader was divorced in 62 BC by Caesar on grounds that “my wife ought not even to be under suspicion”.

Nowadays in our internet-driven culture of public cynicism about our leaders, it is generally accepted that it is not just politicians’ wives who must be above suspicion, but also their wider families. As The National demonstrates today, the late Ian Cameron, the father of the Prime Minister, and David Cameron’s wife Samantha’s stepfather, Viscount Astor, have both been involved in companies that had offshore interests which have now emerged as the result of the Panama Papers.

There is no allegation of impropriety on the part of either man, as the use of offshore funds was and is legal. There may even be many who will no doubt feel that legal avoidance of tax is perfectly legitimate, especially when that tax is used to pay, for example, for Trident nuclear weapons.

That is not the point, however. As David Cameron said in 2012 about the comedian Jimmy Carr who used a Jersey-based tax avoidance system: “Some of these schemes we have seen are quite frankly morally wrong.” Who could disagree?

The Prime Minister must therefore now answer the question, when did he become aware of his father’s use of offshore funds to avoid tax?

Given that Ian Cameron’s use of offshore trusts was well publicised some time after his death in 2010, the Prime Minister cannot hide behind any claim to family privacy. Nor can he say that he did not benefit from his father’s tax avoidance.

The Prime Minister must disclose all his family’s tax affairs, or be accused of, at best, an unconscionable degree of ignorance, or, at worst, rank hypocrisy.

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