On 6 November 1943, the HMT Rohna was sunk by a glide bomb off the coast of Algeria. Of the 1,138 on board who perished, 1,015 were US personnel. A US film about the situation and its cover-up is available on several PBS sites at https://www.pbs.org/show/rohna-classified/.
The losses on the Rohna are second only to the approximately 1,177 dead in the attack on the USS Arizona at Pearl Harbour in December 1941.
At least 29 UK personnel aboard the Rohna lost their lives. The UK government also withheld the truth of the loss. Ann Good, a BIFHSGO member, has researched the UK perspective, which is now documented at https://www.rohnaclassified.com/british-perspective.
In the list of British merchant ship losses, there are at least ten with more British fatalities than the Rohna. The worst UK maritime disaster of the war was the RMS Lancastria, lost on 17 June 1940 with over 3,000, and estimates of 4,000 to 9,000 deaths. The ship, hastily evacuating a mixture of troops and civilians from France, was sunk by aerial bombing.
You may also be interested in this YouTube recording of a Zoom discussion, which included the US producer, two researchers (US/UK), and three British Rohna descendants.