WHEN Brian Fall, Private Secretary at the Foreign and Commonwealth Office (FCO), wrote, in late February 1984, to his counterpart at the Home Office, Hugh Taylor, he spent the second half of the letter impressing upon him the need for secrecy. It was sound advice, given that, in the first half, he revealed that an SAS officer had been advising the Indian government on how to eject Sikh activists from the Golden Temple, the Harmandir Sahib Gurdwara, in Amritsar. The letter, released under the 30-year rule, has been raised by Tom Watson MP: "I think British Sikhs, and all those concerned about human rights, will want to know exactly the extent of Britain's collusion with this period and this episode, and will expect some answers from the Foreign Secretary," he told the BBC Asian Network. A government spokesman said on Tuesday: "The Prime Minister has asked the Cabinet Secretary to look into this case urgently and establish the facts." The letter to the Home Office followed an exchange earlier in February between Mr Fall and Margaret Thatcher's principal private secretary, later Lord Butler of Brockwell. In it, Mr Butler (as he was at the time) wrote: "The Prime Minister is content that the Foreign Secretary should proceed as he proposes. She will look forward to receiving a report on the adviser's visit."

The Cabinet Secretary has first to look at the rest of the correspondence, which remains classified. Second, he has to establish how much influence the SAS officer's report had on Operation Blue Star, the brutal attack on the Golden Temple four months later. Over four days in early June, government forces stormed the temple. The death toll is disputed, but thousands were killed there and during a campaign to stamp out the separatist movement in the Punjab. On 31 October 1984, Indira Ghandi, the Indian prime minister, was assassinated by her two Sikh bodyguards. Hundreds of Sikhs were murdered in mob reprisals over the following few days.

It was a dark episode in India's history, and the involvement of the British Government is acutely embarrassing, especially as the 30th anniversary approaches. The plea for secrecy in Mr Fall's letter indicates that the FCO knew the risk that it was taking. But the British Government was currently negotiating a large arms-deal with India, and the issue of whom they might be used against appears not to have troubled politicians at the time. And it is hard to believe that the religious implications of the desecration of a holy site featured prominently in Herefordshire, the SAS HQ. Interfaith relations in India have improved since that time. The present prime minister is Dr Manmohan Singh. But Hindu nationalism remains strong, and the knowledge that Lady Thatcher's Government had a hand in one of the most bloodthirsty and provocative acts in recent history is greatly disturbing.