Patrick Mercer’s three-year career on the Conservative front bench came to an end after he gave an interview to Times Online about a new antiracism trade union set up for soldiers.

The Tories’ spokesman on homeland security, who came into politics after a long army career, wanted to voice his opposition to the new group, set up by Marlon Clancy, a soldier who complained that he was the target of racist attacks.

Asked about an antiracist trade union, Mr Mercer replied: “Absolute nonsense. Complete and utter rot.” But then he went farther.

He said that suffering racial abuse — as well as abuse about facial features, hair colour and weight — was common in the Army, and to be expected. “I had the good fortune to command a battalion that was racially very mixed. Towards the end, I had five company sergeant-majors who were all black. They were without exception UK-born, Nottingham-born men who were English — as English as you and me.

“They prospered inside my regiment, but if you’d said to them, ‘Have you ever been called a nigger?’ they would have said, ‘Yes’. But equally, a chap with red hair, for example, would also get a hard time — a far harder time than a black man, in fact,” he said.

“But that’s the way it is in the Army. If someone is slow on the assault course, you’d get people shouting, ‘Come on you fat bastard, come on you ginger bastard, come on you black bastard’.”

Mr Mercer added that he knew soldiers from ethnic minority backgrounds who used racism as an excuse for poor performance. “I came across a lot of ethnic minority soldiers who were idle and useless, but who used racism as cover for their misdemean-ours,” he said. “I remember one guy from St Anne’s [Notting-ham] who was constantly absent and who had a lot of girlfriends. When he came back one day I asked him why, and he would say, ‘I was racially abused’. And we’d say, ‘No, you weren’t, you were off with your girlfriends again’.” He added: “In my experience, when you put on the uniform then all differences disappear. If you are a good soldier, you will do well. If you are a bad soldier, you will leave prematurely. There is a degree of colour-blindness among the vast majority of soldiers. I never came across a piece of nastiness inside the battalion that was based exclusively on racism.”

Initially, the Conservative Party responded by playing down the remarks, saying that his comments were a personal matter and refusing to discuss them. It had no relation to his frontbench portfolio. “These are the personal views of a highly decorated, former commanding officer talking about his real life experiences in the Army,” a party spokesman said. Four hours later Mr Mercer was sacked by David Cameron. He said later: “The offence I have obviously caused is deeply regretted. I had the privilege to command soldiers from across the East Midlands of whom many came from racial minorities . . . What I have said is clearly misjudged and I can only apologise if I have embarrassed in any way those fine men whom I commanded. I have no hesitation in resigning my frontbench appointment.”

Conservative leaders over decades have fought to stamp out racism in their party with mixed results.

Days after William Hague urged his MPs to avoid using language “ likely to generate racial or religious hatred”, John Townend, a backbencher, claimed that immigrants were undermining Britain’s Anglo-Saxon culture.

David Cameron has gone far further than any of his predecessors to make the Conservatives more inclusive — trying to recruit more ethnic minority candidates, introducing ethnic monitoring of staff, and taking a robust stance in race rows.

He recently told an ethnic media conference that there was less racism in politics than there used to be, but that it still existed in all parties. “The difference is that now we regard it as entirely unacceptable.”

But the issue still dogs the party. Last year, Bernard Jenkin MP, who was in charge of candidate selection, caused outrage by suggesting that an Asian candidate would not be chosen for a seat because he was not a white male. When a councillor e-mailed a derogatory poem about asylum-seekers, Mr Cameron suspended her from the party.

Part of the problem is that, as modernising MPs admit privately, racism still pervades parts of the party. Grassroots activists in particular are notorious for being reluctant to embrace Mr Cameron’s modernising message, as are some of the more right-wing MPs.

The long history of race rows makes any new incidents particularly damaging for the Conservatives, allowing opponents to claim that they are the “same old Tories”. Only by acting decisively and quickly, as Mr Cameron has tried to do, can the party show that it takes the issue seriously.

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