Alexander was born on 1 February 1923 in Newton Abbot, Devon to Manchester born Samuel, a travelling cotton salesman, and Kathleen (Kitty) née Barrett and had a younger brother Michael. Their father Samuel was previously married to Dora Cohen, who died in 1920, and they had two children Daniel and Maud ‘Alty’. In 1921, the family were living in Torquay, Devon and Kitty was working as the housekeeper. Kitty and Samuel married a year later in Willesden, London. In 1939, Alexander was living in Islington with his family and he was working as a furniture shop assistant. In 1940 he enlisted into the RAFVR.

Alexander was the observer on Lancaster ED319 which departed RAF Scampton on a night operation to Essen. During the inbound flight over Holland they encountered Luftwaffe night fighters. The aircraft was intercepted by Lt. Erich Richter of 2./NGJ his second claim of the war. The aircraft crashed at Haarzuilens 12 km NW of Utrecht with the loss of all crew.

Pilot, Sgt. David Stanley Warlow, RNZAF, 414705
F/E, Sgt. Vincent John Mervyn Donaldson, 574813
Nav, Sgt. Alexander Jacobsen
A/B, Sgt. Robert Elwyn Roberts, 1389926
W/Op A/G, Sgt. Jack Webber, 1377524
A/G, Fl/Sgt. William Albert Gillen, RCAF, R/135059
A/G, Sgt. George Roe, 1576603