Cabinet member Hilary Armstrong said last week that war was “not a matter of conscience”. The outburst came when Armstrong, Labour’s Chief Whip, responsible for ensuring backbenchers support the government in the House of Commons, called MP Paul Marsden into her office to give him a dressing down.

Armstrong berated Marsden for publicly opposing the war in Afghanistan, threatening him, “Those that aren’t with us are against us.”

On October 13, the backbench Labour MP spoke out against the war at a march and rally organised by CND in London that attracted up to 50,000 protestors. Prior to this on October 8, in the third debate on the “international coalition against terrorism”, Marsden had raised a point of order calling for a Commons’ vote on the conduct of the war. Marsden also asked, “When will British citizens be given a written constitution so that Parliament, not a prime minister, authorises a declaration of war?” Both questions were brushed aside.

The lengths to which the government is prepared to go in stifling opposition to its war drive is revealed by last week’s exchange in the Chief Whip’s office, which Marsden subsequently passed on to the press.

Armstrong: “We may hold a vote [on the war]... but it will be whipped [i.e., support for the war would be made compulsory for Labour MPs].”

Marsden: “That is outrageous. You won’t even give us a free vote on whether we go to war, which should be a matter of conscience.”

Armstrong: “War is not a matter of conscience. Abortion and embryo research, they are matters of conscience.”

Marsden: “Are you seriously saying that blowing people up and killing people is not a moral issue?”

Armstrong: “It is government policy that we are at war... anyway you must stop using the media.”

Marsden: “That’s a bit rich coming from people like you and Downing Street when [Transport Secretary] Stephen Byers’ spin doctor Jo Moore says September 11 is a good day to bury bad news.”

Armstrong: “Jo Moore didn’t say that.”

Marsden: “That is exactly what she said in her email.”

Armstrong: “We don’t have spin doctors in No 10 [Downing Street], or anywhere else.”

Marsden: (laughing) “You aren’t seriously telling me that you don’t have spin doctors and they don’t exist. You are losing it, Hilary.”

Armstrong: (shouting) “You wait until I really do lose it. I am not going to have a dialogue with you about that. It was people like you who appeased Hitler in 1938.”

(The Whips take their name from the “whippers-in”, who kept hunting hounds in line. Labour Whips are answerable directly to the prime minister, until recently being housed adjacent to his official residence at No 10 Downing Street. When they call a “three-line whip”, every Labour MP is required to attend the Commons to support the government in any vote.)

Not only did Marsden refuse to submit to the Chief Whip’s remonstrations, he then provided the press with his own verbatim account of the confrontation. This is considered an almost unpardonable breach of parliamentary etiquette, according to which the actions of the Whips are not subject to any public scrutiny.

Foreign Secretary Jack Straw, who had been the first government member to liken those opposing the war with supporters of appeasement with Nazi Germany, also attacked Marsden for publishing his account of what Straw described as a “private conversation” with the Chief Whip.

Following publication of the exchange between Armstrong and Marsden in the Mail on Sunday, armed forces minister Adam Ingram told Sky television that Labour MPs opposed to the bombing were “moving towards” those who appeased the Nazi regime in the 1930s.

The pressure was kept up on Monday, when Defence Minister Geoff Hoon said, “Labour members... know what are the consequences of crossing the Whips and abandoning party policy.”

Donald Anderson, Labour chairman of the Commons select defence committee, also told the press: “when one does dissent in times of war, it can help the enemy.”

However, Marsden stood by his call for a parliamentary vote, saying Monday, “My view is that we should have free and open debate. What on earth is the government so afraid of? Why on earth can’t we have a vote in the Commons? The last Conservative administration had a vote on the Gulf war.”

Having determined that they were unable to silence him, the government then set about blackening Marsden’s reputation. The Guardian wrote, “Mr Marsden now faces more insidious assaults from Labour’s spin machine. The whispers are out already that the gardening enthusiast is unpopular with colleagues and is even emotionally unstable.”

In the affairs of state, if there is one single act that could be considered a matter of conscience, then it is the decision to launch a war against a foreign country, in which thousands upon thousands of lives are at stake, both abroad and at home. By way of comparison, when it comes to restoring the right of the state to take the life of a convicted murderer MPs have always been able to cast their ballot according to their own beliefs. Every vote on restoring capital punishment since it was abolished in Britain in 1965 has been a free vote.

Yet now, having launched the war against Afghanistan in the name of defending democracy against terrorism, Labour has shown the extraordinary lengths to which it is prepared to go in order to stamp on even the slightest criticism from within its own ranks.

This has proved highly embarrassing for the Labour leadership. At the same time that Marsden’s integrity and even his sanity were being questioned, therefore, the prime minister’s office sought to distance Blair himself from the affair. Officials were said to be “embarrassed” at having to defend what was regarded as Armstrong’s “heavy-handed” approach. The prime minister’s spokesman said, “The prime minister doesn’t have any trouble with people expressing their views even if they contrary to stated government policy.”

Such statements are a transparent evasion. Given the close working relationship between the Whips’ Office and the prime minister, it is highly unlikely that Marsden’s carpeting had not been discussed with No 10. For one brief moment, the curtains parted, behind which much of official politics are conducted. What was revealed was not so much the “black arts” practised by the Whips’ Office, as the media disingenuously puts it, but the venal and anti-democratic character of the Labour government.