I've read it in memoirs from 8th Army veterans.
From Tanks-encyclopedia.com
The M3 (Stuart Mk.I and Mk.II – Honey tank)
The M3 was the first production model. Most of these were provided to the British and Commonwealth forces through Lend-Lease. Some were immediately thrown into action in Northern Africa, where they immediately became popular for their speed, sturdiness and reliability. Although the official British designation was “Stuart”, paying homage to Civil War Confederate General J.E.B. Stuart, they found themselves affectionately dubbed “Honey”, because of their smooth ride. Some authors say that it was not called the ‘Honey’ during the war but military historian Ed Webster has found official British wartime documents in the archives that use the name ‘Honey’. He also found a number of wartime newspaper entries where the reporters used the name ‘Honey’ when talking about the M3 Stuart: The Scotsman, Wednesday 26 August 1942, ‘Leaving the desert track he swept over the desert in a Honey tank, with brigade pennant flying…’; Yorkshire Post and Leeds Intelligencer Wednesday 26 August 1942, Same text ‘Leaving the desert track he swept over the desert in a Honey tank, with brigade pennant flying…’: Daily Herald Monday 07 September 1942, ‘Here is a United States built Honey Tank speeding at the foot of this insignificant-looking but coveted hill….’; Belfast News-Letter, Wednesday 26 August 1942, ‘Mr Churchill swept over the desert in a Honey tank, with brigade pennant flying…’; Perthshire Advertiser, Wednesday 28 April 1943, ‘I was just wondering what to do with this party when one of our gunner observation posts came up in a Honey Tank….’ The ‘Honey’ nickname never stuck with the US Military. Despite this, all following tanks provided to the British received a Secession War general name and the tradition stuck up to 1945, finally being adopted by the US army itself.