Professor Nutt on the resignation of other members of the Advisory Council
A second adviser to the government has resigned in protest at Home Secretary Alan Johnson's sacking of his chief drugs adviser, Prof David Nutt.
Marion Walker's departure from the Advisory Council on the Misuse of Drugs (ACMD) followed the earlier resignation of Dr Les King.
Dr King said he would like to see the ACMD become an independent body, free from the government's influence.
Mr Johnson said Prof Nutt was sacked for "crossing a line" into politics.
On Sunday, Prof Nutt revealed Ms Walker, ACMD member from the Royal Pharmaceutical Society, had stepped down. However, she could not be reached for comment.
I'm not going to say just how many I think might resign but there is an extremely angry feeling among most council members
Dr Les King
Ms Walker is clinical director of Berkshire Healthcare NHS Foundation Trust's substance misuse service.
Prof Nutt said her departure "means we have no-one now looking at that vast group of people who prescribe drugs and advise people about drugs, drug harms from the over-the-counter and prescription side".
The BBC understands that several other members of the ACMD, who are unpaid for their work on the council, are considering their positions, in response to Prof Nutt's dismissal.
Prof Nutt was sacked after calling cannabis less harmful than alcohol and tobacco, and saying it was upgraded to Class B for political reasons.
The reclassification had been "on the whim of the prime minister", he claimed.
There was "very strong feeling" among the council's members over Prof Nutt's sacking, Dr King said.
"I'm not going to say just how many I think might resign but there is an extremely angry feeling among most council members.
"Amongst the scientists, I think a number will resign. It doesn't need the whole council to resign for the thing to stop working."
He also said the ACMD should become independent "just as the National Institute for Clinical Excellence is separate from government and is free to make decisions, free of political interference, just as... the Bank of England is free to make decisions on interest rates.
"That's what we need I think, because the classification of drugs is about drug harm. It doesn't need to be politicised in the way that it is."
Dr King was appointed on 3 April 2008 and wrote a book on the Misuse of Drugs Act in 2003. He was previously head of the Drugs Intelligence Unit in the Forensic Science Service.
Prof David Nutt - chairman of the Advisory Council on the Misuse of Drugs
Dr Les King - part-time advisor to the Department of Health, senior chemist on ACMD
Marion Walker - clinical director of Berkshire Healthcare NHS Foundation Trust's substance misuse service, Royal Pharmaceutical Society's representative on ACMD
Prof Nutt has told the BBC that the council's position is "untenable".
He said: "I think the position of scientists on the council's untenable, because I cannot see how Alan Johnson, given what he's just said, which clearly indicates he doesn't understand how scientists think, how scientists on council could continue to work with him."
Confirming Dr King's resignation, the Home Office said in a statement: "We're not going to give a running commentary on the speculation around further resignations. We will not be commenting further."
Speaking to Sky News on Sunday, Mr Johnson said he thought his ex-chief drugs adviser was "wrong" on cannabis - but sacked him for "crossing a line" into politics.
"What you cannot have is a chief adviser at the same time stepping into the political field and campaigning against government decisions. You can do one or the other. You can't do both."
Mr Johnson said that Prof Nutt had "crossed the line between offering advice and then campaigning against the government on political decisions".
Dr Les King speaks out in support of David Nutt
But Labour peer Lord Robert Winston told BBC Radio 4's The World This Weekend he was "very surprised and disappointed" by Mr Johnson's actions.
He warned that the government would be ignored if it gave advice to the public that did not take account of scientists' opinions and said Prof Nutt had made a "very reasonable" point about the relative dangers of illegal and legal drugs.
Lord Winston, professor of science and society at Imperial College London, said: "I think that if governments appoint expert advice they shouldn't dismiss it so lightly. I think it shows a rather poor understanding of the value of science."
Dr Evan Harris MP, Liberal Democrat science spokesman, said: "I fear there will be many more resignations unless the government acts to restore confidence among its independent scientific advisers, upon which it relies for advice on matters from nuclear safety to childhood vaccination."
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