HOME Secretary Alan Johnson may live to regret the hasty sacking by email of his chief drugs adviser, Professor David Nutt, for saying that cannabis is less harmful than alcohol or nicotine.

We can understand Mr Johnson being miffed that his scientific advisor should undermine the Government’s decision to upgrade cannabis to Class B, claiming the reclassification had been for political reasons and “on the whim of the Prime Minister”.

It is certainly straying into the political arena for Professor Nutt to make such a statement.

But Mr Johnson appears to have underestimated the reaction among scientists to Professor Nutt’s sacking.

Marion Walker last night joined Dr Les King in quitting the Advisory Council on the Misuse of Drugs, arguing that Professor Nutt had been denied his “freedom of expression”, and other resignations may follow.

All of which begs serious questions about the ground rules which apply to Government advisors. By agreeing to guide the Government on areas of expertise, are they duty bound to keep their mouths shut when they disagree with Government policy?

Clearly, Professor Nutt does not believe he was bound by any such agreement, and neither do Dr King and Ms Walker.

It adds up to an untimely mess for the Government, which needs all the friends it can get. If their decisions are to be taken seriously, ministers have to take account of scientific advice on all kinds of issues.

Instead of the sack, a mature discussion with Professor Nutt about the parameters of his relationship with the Government could surely have avoided this embarrassment.