I wrote in I Think I Prefer the Tinned Variety: The Diary of a Petty Officer in the Fleet Air Arm during World War II about some of the abbreviation's my dad had used in his diary. The most difficult to interpret was P.D. (See previous post).
More on the subject of "pack drill".
A member of the WW2Talk forum pointed me in the direction of Hansard (the record of Parliamentary debates which is available on-line) where there are a couple of interesting references.
In April 1943, Mr Walter Edwards (1900 - 1964), the M.P. for Stepney and Whitechapel, asked the First Lord of the Admiralty if pack drill was being used as a form of punishment in the Royal Navy. The First Lord of the Admiralty gave him a categorical assurance that it was not and had never been used as a form of punishment in the Royal Navy.
In July 1946, Mr Jack Lawson (1881 - 1965), M.P. for Chester-le-Street and briefly Secretary of State for War (1945 - 1946) assured the House of Commons that pack drill had been abolished in the British Army in 1930; there was however some dispute in 1946 that the punishment was still in use in the army in India.
So…it seems highly unlikely that in my dad's diary he was using the abbreviation "P.D." to stand for pack drill but it has proved an interesting line of inquiry nonetheless.