Derek was born on 29 August 1922 in Willesden to Harry Diamondstein and Sadie nee Abrahams and he had an older brother Ralph who served in the Royal Fusiliers. Derek attended Kilburn Grammar School and was a member of Maccabi. In 1939 the family lived at 22 Clarendon Court, Willesden where their father Harry was a sales manager at a furrier shop and Derek worked as an articled draughtsman.

Derek was on board R.M.S. Laconia which was transporting troops to the Middle East. The ship was carrying a 136-man crew, 80 civilians, military material and personnel (268 men) and approx. 1800 Italian prisoners of war with 160 Polish soldiers on guard. U Boat 156 torpedoed the ship and shortly after the sinking the crew of the U boat were amazed to hear Italian voices in the sea amongst the people both in lifeboats and also struggling in the water itself. Werner Hartenstein the captain immediately began rescue operations and radioed for assistance, both from nearby U-boats and also sent out un coded messages to every vessel around to assist, promising to cease hostilities. In the next days U-156 saved over 400 survivors, holding 200 on board and the other 200 in lifeboats. On Sept 15, at 1130 hours U-506 under the command of Kptlt Erich Wurdemann arrived at the scene and continued to rescue the survivors. A few hours later U-507 under Korvkpt. Harro Schacht and the Italian submarine Cappellini also arrived. The boats headed for shore, towing the lifeboats behind them and hundreds of survivors were both in and inside the U-boats themselves. On Sept 16, at 1125 hours an American B 24 Liberator bomber operating from the Ascension Island arrived at the scene where its pilot spotted the boats (which at that time flew the Red Cross flag and were clearly not hostile to anyone). The pilot radioed back to his base asking for instructions and was told to attack at once which he did at 1232 hours, forcing the U-boats to cut the lines to the life boats and submerge immediately, leaving hundreds of people again struggling in the water. Thankfully this US intervention caused not as much loss of life as it could have as shortly afterwards some neutral French warships from Dakar arrived at the scene and started picking up survivors. Also many had been taken into the U-boats themselves and were safe there (only because the bomber failed to sink them though). Roughly 1500 survived the sinking. Source: uboat.net – Articles