"Politically retarded" Tory tacticians are taking the Conservatives to oblivion, warns a former party chairman today.

Writing in today's Spectator, Lord Tebbit attacks Iain Duncan Smith's attempts to modernise the Tories.

"The politically-retarded managers at Central Office seem obsessed with the ethnic and sexual minorities forgetting that those who share our values will come with us and those who won't will not," he writes.

"Despite the ramblings and spoutings of the over-excitable and scarcely rational children in Central Office, the nation is not possessed by an overwhelming urge to fill the shadow cabinet with 25-year-old black lesbians and homosexual asylum-seeking Muslims."

The former cabinet minister and party boss from the Thatcherite heyday is regarded by some true blue Tories as a custodian of the Conservative soul.

His criticism of the new Tory leader's attempt to turn to "vulnerable people" and minorities may strike a chord with provincial party associations in the run up to a testing autumn conference for Duncan Smith.

"If [the conference] is all tactics and minority-chasing tomfoolery, the Tories will cease to be a grown up party," he claims.

Pointing to the collapse of the centre right in New Zealand, Tebbit argues that the new Tory leader has lost sight of the party's core values.

"Wildly arcane arguments that are remote from the concerns of our supporters - or potential supporters - outside Westminster", he says, are to blame for continuing the Conservative exile in the political wilderness," he writes.

"It is their tactics and presentation which are plaguing the Tories and turning off the electors.

"The challenge for Iain Duncan Smith is to raise his game, end the petal plucking 'they love us, they love us not' introspection and set out the red meat of politics - the principles and policies on which we would govern."

Tebbit expresses incomprehension at the decision of frontbench MP, Alan Duncan, to "come out" as gay.

"The great mass of us have no desire to emulate Mr Duncan's activities under his duvet; we do not think it our business exactly what he does do there; we do not wish to join in; we just wish profoundly that he would not bore us with his sexual problems," he said.