LONDON, JUNE 13 -- Less than a year after he resigned from her cabinet, one of Prime Minister Margaret Thatcher's closest political advisers today was named chairman of a major telecommunications company that had been privatized by Thatcher's government, touching off a new debate here over conflict of interest.

The appointment of Lord Young, until last month deputy chairman of the Conservative Party, as head of Cable and Wireless PLC makes him the fifth former Thatcher cabinet member to join the board of a formerly publicly held company privatized by her government. While serving as trade and industry secretary, Lord Young granted the company one of the licenses to set up a British network of mobile phones.

His appointment brought harsh criticism from the opposition Labor Party, which has introduced a bill in Parliament requiring a five-year waiting period before former cabinet ministers can join companies privatized while they served in government.

"Privatization sleaze has now become a major electoral issue," said Gordon Brown, Labor's spokesman on trade and industry issues. He said Lord Young's appointment meant the former official "will spend time negotiating on behalf of Cable and Wireless with the very department he left only a year ago."

But Thatcher defended the "revolving door" of ministers moving into business, saying it has been a longstanding practice defended by such Labor prime ministers as Harold Wilson.

"Successive governments have taken the view that it is valuable for the people of this country to have those who have great experience in public affairs to put their talents to the service of industry, and for those who have experience of industry to put their talents at the service of the government," she told the House of Commons Tuesday.

Former cabinet minister Norman Tebbit, who sits on five different boards of directors while still serving in Parliament, was far more combative. Writing in today's Evening Standard, he accused critics of a "smear campaign," adding: "Labor is a party full of envy, peopled with failures and richly tainted with smug hypocrisy."

"If anyone believes I de-nationalized British Telecom and three years later gave up a 50,000 pound-a-year cabinet post just to get a 16,000-pound-a-year job as a non-executive director, he must be either daft or too full of political spite, malice, spleen and envy to be rational," wrote Tebbit.

Analysts say there is nothing new about retired British cabinet ministers making their way into boardrooms and, indeed, virtually every large British company or bank boasts at least one member of Parliament on its payroll. But the Thatcher cabinet is special, they say, because some former ministers are becoming executives or directors of companies that they were responsible for setting up as government officials.

British civil servants are required to wait two years after leaving their posts before being allowed to work for the companies they dealt with in government. But there are no such strictures on cabinet ministers or members of Parliament.

Members of the House of Commons, who earn about $45,000 a year in a job that has become virtually full time, are required to make public disclosure of outside business activities but are not restricted from accepting directorships or other positions.

Those who also serve as cabinet ministers earn about $94,000 and are under a supposedly stricter code of ministerial conduct formulated by the cabinet but kept confidential.

Despite the looseness of the law, members have come under increasing pressure in recent years to avoid appearances of conflict.

Michael Mates, chairman of the powerful House Select Committee on Defense, recently resigned as consultant to a company offering guidance to arms manufacturers after another lawmaker accused him in Parliament of being "a paid servant" of the company.