The June 1984 attack on Sri Harmandir Sahib - popularly referred to as the Golden Temple complex - in Amritsar caused a legacy of pain and grief that Sikhs still feel profoundly today. So as Theresa May prepares to visit India this weekend it is vital she is open, honest and transparent about the role Margaret Thatcher's administration may have played in the months leading up to it and the terrible events that followed.
The Golden Temple is the Sikh religion's holiest site. Sikhs believe thousands were killed when it was attacked by the Indian army - 11,000 pairs of unclaimed shoes were found at the site. Thousands more were murdered across India in the violence that followed.
Sikhs have been trying ever since to obtain a full and accurate picture about the circumstances that made such a sustained and systemic outbreak of violence possible, including many who lost friends and relatives. The determination and persistence of the Sikh community in the UK and overseas has also forced the Government to answer questions about the true extent of British involvement. But sadly, those answers are still incomplete.
A 2014 review by a senior Whitehall official found that the UK's involvement was limited to a single visit by a British military advisor to India in February 1984.
But we learned on Friday that a series of files placed by the Foreign Office in the national archive this summer have been removed by the Government after their contents were brought to Boris Johnson's attention by the Sikh Federation (UK).
They include a note written by a British civil servant a month after the Amritsar attack took place which referred to the SAS in the context of a request from India for help in setting up a National Guard. Other files that have been removed relate to a meeting between Margaret Thatcher and Indira Ghandi, who was then India's Prime Minister, and details about arms sales to India.
The Foreign Office claims those files have simply been removed so that civil servants can exam them. Perhaps that is the case. But it is extremely unusual for documents to be recalled by a Government department a few months after being cleared for release. This is the only example I have ever come across of documents being withdrawn in this way.
The reference to the SAS is highly significant because it implies that there could have been a level of collusion between India and the UK that was specifically ruled out by the 2014 review. When he announced its findings in Parliament, the then-Foreign Secretary William Hague assured the House there was no further evidence of British assistance or advice to India. If Lord Hague, as he now is, mistakenly misled Parliament I know he will want to put that right as soon as possible.
The easiest way to find out if MPs were misled, of course, is for the Government to publish the files immediately, or place them back in the National Archives where they belong. I will be writing to the Government to suggest it does just that.
I will also be raising questions in Parliament about why these files were removed, whether their removal was requested by a Minister and when they will be returned.
The events of 1984 caused a huge amount of pain. The government has a duty to the UK's Sikh community to be transparent about the events of the past and honest about the part this country may have played in them.
Our government has insisted in the past that domestic security issues are a matter for India, but we have known since 2014 that the UK had some military involvement and it can no longer fall back on that excuse.