Britain’s civil service embarked on an 18-year quest for the perfect toilet paper after a doctor voiced concern about a diplomat’s hemorrhoids, according to a government file made public.

John Hunt, a London physician, wrote to the Treasury’s medical adviser in 1963 after he examined Sir John Pilcher, who was Britain’s ambassador to Austria and, later, Japan, the Daily Telegraph reported.

“A patient of mine … thinks that the government lavatory paper is out of date and extremely bad for his complaint (hemorrhoids) and he has asked me if there is any chance of it being changed to a softer type,” Hunt wrote.

It soon emerged that Her Majesty’s Stationery Office, in charge of buying all government toilet paper, preferred the rough stuff because it cost the taxpayer less.

A lively correspondence followed, involving such interested parties as combative staff unions, the august School of Hygiene and Tropical Medicine (which thought hard, shiny paper was better) and the Treasury typing pool.

In the 1970s, “creped paper” gained favour as the price factor evaporated. Then in 1980, a team of epidemiologists weighed in with a report that argued that soft paper was more hygienic.

The following year, soft paper made its debut in government toilets, bringing relief to countless bureaucratic bottoms.

The hefty dossier was among 50,000 files brought to light Tuesday by the National Archives in Kew, west London under a Freedom of Information Act that came into effect on New Year’s Day.