Musical Instruments Carried by British Soldiers?

Wonder if there was a piano tuner handy!

 

Heres another instrument to ponder. Deep in Burma, February 1945, the 9th Battalion, Royal Sussex are heading for Mongmit, still chasing the Japanese. A brief pause at Athan before they head for Mogok. Cyril Grimes records in his diary-
" Thursday 15th March: An accordionist from the RA's came over in the evening, and we had a sing song at the edge of the stream. Fires in the hills all around made a grand spectacle at night."
Doesn't it conjure up a picture of a happy moment, when suddenly fires and singing is allowed because the enemy are in retreat.
Who was that man with the accordion?