In 1934, then a graduate student at King's College London, he wrote his PhD thesis on Trade and War in the Eastern Seas, 1803–1810, which was awarded the Julian Corbett Prize in Naval History for 1935.

While a graduate student in 1934, Parkinson was commissioned into the Territorial Army in the 22nd London Regiment (The Queen's), was promoted to lieutenant the same year, and commanded an infantry company at the jubilee of King George V in 1935.

Parkinson attempted to persuade the authorities to avoid dividing the university by maintaining it in Johor Bahru to serve both Singapore and Malaya.

To avoid high taxation in Britain, he moved to the Channel Islands and settled at St Martin's, Guernsey, where he purchased Les Caches Hall.

[5] His writings from this period included a series of historical novels featuring a fictional naval officer from Guernsey, Richard Delancey, during the Napoleonic era.

"In exactly the same way nobody bothered and nobody cared, before Newton's day, why an apple should drop to the ground when it might so easily fly up after leaving the tree," wrote Straits Times editor-in-chief, Allington Kennard, who continued, "There is less gravity in Professor Parkinson's Law, but hardly less truth.

"[8] Parkinson first published his law in a humorous satirical article in The Economist on 19 November 1955,[1] meant as a critique on the efficiency of public administration and civil service bureaucracy, and the continually rising headcount, and related cost, attached to these.

That article noted that, "Politicians and taxpayers have assumed (with occasional phases of doubt) that a rising total in the number of civil servants must reflect a growing volume of work to be done."

[10] The advent of his new book as well as an interview during his debut talk was covered in an editorial in The Straits Times shortly after, entitled, "A professor's cocktail party secret: They arrive half an hour late and rotate."

Orgmanship, according to Parkinson, was "the tendency of all administrative departments to increase the number of subordinate staff, irrespective of the amount of work (if any) to be done", as noted by The Straits Times.

[11] Straits Times editor-in-chief Allington Kennard's editorial, "Twice the staff for half the work", in mid-April 1958, touched on further aspects or sub-laws, like Parkinson's Law of Triviality, and also other interesting, if dangerous areas, like "the problem of the retirement age, how not to pay Singapore income tax when a millionaire, the point of vanishing interest in high finance, how to get rid of the company chairman," etc.

The author supported Parkinson's Law of Triviality – which states that, "The time spent on any item of an agenda is in inverse proportion to the sum involved," with a local example where it took the Singapore City Council "six hours to pick a new man for the gasworks and two and a half minutes to approve a $100 million budget.

"[14] And then, all of a sudden, satire was answered with some honesty when, as another Reuters release republished in The Straits Times under the title "Parkinson's Law at work in the UK," quoted, "A PARLIAMENTARY committee, whose Job is to see that British Government departments do not waste the taxpayer's money, said yesterday it was alarmed at the rate of staff increases in certain sections of the War Office.

[28] Sponsored by the Malayan Historical Society, Parkinson gave a talk on the "Modern history of Taiping" at the residence of the District Officer, Larut and Matang on 12 August 1953.

He said that mining developed steadily after British protection had been established and that tin from Negri Sembilan in the 1870s came from Sungei Ujong and Rembau, and worked with capital from Malacca.

In his lecture, he argued that nationalism which was generally believed to be good, and colonialism which was seen as the reverse, were not necessarily opposite ideas but the same thing seen from different angles.

He thought the gifts from Britain that Malaya and Singapore should value most and retain when they became self-governing included debate, literature (not comics), armed forces' tradition (not police state), arts, tolerance and humour (not puritanism) and public spirit.

[35][36] On 18 August 1950, Parkinson opened a week-long exhibition on the "History of English Handwriting," at the British Council centre, Stamford Road, Singapore.

[40] 140 photographs were on display for a month at the British Council Hall, Singapore, showing scenes ranging from the German surrender to the opening of the Festival of Britain by the late king.

[42] Towards the end of August, Professor of Far Eastern History at Cambridge University, Dr. Victor Purcell, who was also a former Acting Secretary of Chinese Affairs in Singapore, addressed the Kuala Lumpur Rotary Club.

[44] In November, Parkinson was appointed a member of the committee for the management of Raffles Library and Museum, replacing Professor G. G. Hough who had resigned.

[45] In March 1952, Parkinson proposed a central public library for Singapore as a memorial to King George VI, commemorating that monarch's reign.

[57] At the beginning of December 1950, Parkinson made an appeal at the Singapore Rotary Club for old log books, diaries, newspaper files, ledgers or maps accumulated over the years.

In his letter, Parkinson, who was still abroad in London attending the Anglo-American Conference of Historians, said that the formation of an archives office was already in discussion, and was urgent, in view of the climate where documents were liable to damage by insects and mildew.

He noted that cockroaches had nibbled away at many vital documents and records, shrouding many years of Malaya's past in mystery, aided by moths and silverfish and abetted by negligent officials.

According to the news report a large-scale project, developing a ten-volume series, the result of ten years of research by University of Malaya staff, was currently in progress, detailing events dating back to the Portuguese occupation of 1511, to the, then, present day.

The report noted that, as at that time, Parkinson and his wife had already released two books on history for junior students, entitled The Heroes and Malayan Fables.

Departing from the usual syllabus, Parkinson had decided to leave out European History almost entirely in order to give greater focus to Southeast Asia, particularly Malaya.

If we can, from this university, send forth graduates who can combine learning and ways of thought of the Far East and of the West, they may play a great part in overcoming the barriers of prejudice, insularity and ignorance," he concluded.

Parkinson signed a notice that noted that some of the rioters who took part in the December disorders came from an area near the university buildings in Bukit Timah.