Depicting typical British scenes of the time, they were intended to bring hope to his companions, many of whom were on the brink of death.
One colourful sketch captures a day at the races, while another depicts a plump landowner with his hunting party.
Another appears to show an Elizabethan court, while a fourth shows cavemen on horses with the joke, ‘Definitely the first polo match!’
The cartoonist, who died two months ago, entrusted them to the camp’s senior officer, Major Patrick Malins, who kept them with his own journal.
His family discovered the mementoes only after the major’s death and they will be shown for the first time on Antiques Roadshow tomorrow.
Pauline Malins, the late major’s daughter-in-law, showed the cartoons to programme experts when they visited Lulworth Castle, Dorset.
She said: ‘It must have been what kept them going – the distant hope of one day returning to life back home in Britain’
Antiques Roadshow: Sunday March 4 on BBC1 8pm."
"Pauline Malins brought along some sketches by Ronald Searle, who was in the same Japanese Prisoner of War camp as her late father-in-law, major Pat Malins. Book expert Rupert Powell was fascinated to see them along with Pat’s diary – but to find out the value you’ll have to wait until the second compilation from Lulworth, later in the series."