Workers would shout 'Basil' at him - mimicking Sybil Fawlty's nagging of her husband in classic comedy Fawlty Towers.
Mr Basile's boss - with whom he had an "uneasy relationship" - would also make crude "sexual hand gestures" and greet him with the words "How's it hanging?"
Mr Basile alleged that other workers called him "French w***er" and French "t***er" and would comment "sorry he's French" when there were misunderstandings.
A tribunal panel concluded that Inspector Clouseau - played by Peter Sellers in the Pink Panther film series - was a "British comic creation of a stereotypically bumbling French character".
It concluded that it was reasonable for Mr Basile, who spoke with a distinct French accent, to consider this nickname "humiliating".
The panel at Central London Employment Tribunal found the College and manager Nicholas Rogers guilty of sexual harassment and sex discrimination.
Mr Basile is seeking five figure compensation for injury to his feelings. And his lawyers claim the College is facing a potential total bill of around £100,000 when legal costs are taken into account.
After an eight-day tribunal hearing, the college unsuccessfully appealed the judgment at the Employment Appeal Tribunal.
Founded in 1952, the College is the professional body for UK family doctors with over 42,000 members.
It is a registered charity whose patron is the Duke of Edinburgh and its motto is 'Cum Scientia Caritas' - 'Scientific knowledge applied with compassion'.
Mr Basile, in his late 30s, worked as a porter at its HQ in South Kensington, south-west London from 1999 until his redundancy in 2010.
Facilities for the use of member doctors at the HQ included a bar, dining room, library and overnight accommodation and the premises regularly staged conferences and functions.
The tribunal panel found that although Mr Basile has lived in London since 1998 he speaks with a "discernible French accent".
Over a four-year period, Mr Basile was called 'Inspector Clouseau' by employees, including Mr Rogers.
The panel ruled: "The particular choice of nickname, being that of a British comic creation of a stereotypically bumbling French character, who speaks with a heavy accent, was, we had no doubt, materially influenced by Mr Basile being French.
"This was conduct which, we also had no doubt from his evidence, created a humiliating environment for Mr Basile."
It also found: "The name 'Basil' was on occasion shouted at him in a manner intended to be a humorous reference to the hectoring of Basil by Sybil Fawlty in Fawlty Towers".
Mr Rogers would make offensive sexual hand gestures that Mr Rogers found upsetting because he believed they were directed at him.
The tribunal said of the 'How's it hanging' taunt: "The greeting was, we found, directed at Mr Basile and intended to tease or mock him in a manner laced with an element of sexual innuendo."
On one occasion, Mr Basile was away in France for medical treatment. He was signed fit to return to work by a doctor but told not to lift anything heavy.
Mr Rogers asked him: "If you can't do your job, what are you doing at RCGP?" The tribunal said his question was "symptomatic of their uneasy relationship".
Mr Basile did not make any formal complaint about his boss because he did not think anything would be done.
Discrimination claims normally have to be brought within three months of the act complained of.
The tribunal ruled that Mr Basile was too late to succeed in a claim of race discrimination in respect of the Inspector Clouseau nickname.
But it chose, exceptionally, to allow his sex discrimination and sexual harassment claims in respect of the greeting and gestures even though they were also out of time.
Mr Basile failed in a claim for unfair dismissal in relation to the redundancy process. He lost his job ahead of the College's move to a new HQ in the City of London.
A remedy hearing is due to take place this summer.
The College chose not to comment on the judgment.
Asked about its estimated £100,000 bill, a College spokesperson said: "Costs to the College have been kept to a minimum on this issue as it was also able to use in-house expertise on the case."