One of the most popular American situation comedies of the late 1970s, running for no less than eight seasons, is “Three’s Company.” The series, originally starring Joyce DeWitt, Suzanne Somers, and John Ritter, revolved around three roommates.

In 1981, following Somers’ departure, Jenilee Harrison joined the cast. Harrison was not with the cast very long. Not long after joining the cast, she was replaced by Priscilla Barnes.

Somers and Harrison were not the only one to leave the show.

With Norman Fell and Audra Lindley leaving the series to head up a spin-off situation comedy of their own, “Three’s Company” needed a new landlord. Don Knotts joined the cast to fill that requirement.

While there is no doubt “Three’s Company” was hugely popular, it was by no means an original concept.

“Three’s Company” was a remake of the British situation comedy “Man About the House.”

“Man About the House,” starring Richard O’Sullivan, Paula Wilcox and Sally Thomsett, ran for six series.

Where Norman Fell and Audra Lindley played the Ropers in the American production, in the original British version of the series, those characters were played by Brian Murphy and Yootha Joyce.

Created and written by Brian Cooke and Johnnie Mortimer, “Man About the House,” was an ITV production televised from 15 Aug. 1973 to 7 April 1976.

Interestingly, both “Man About the House” and “Three’s Company” saw two spin-off series which followed virtually identical premises.

Murphy and Joyce starred as the title characters in “George and Mildred.” The show ran for five series.

Like many British sitcoms of the time, “George and Mildred” was also made into a television film. The film was dedicated to Joyce who died suddenly in August 1980. At the time of her death, the cast was preparing to record a sixth series.

The American version of “George and Mildred” was “The Ropers.”

“The Ropers,” starring Fell and Lindley, picked up their story from the point of the characters leaving “Three’s Company.” Unfortunately, for both Fell and Lindley, “The Ropers” was short lived. Their spin-off show never attained the popularity “Three’s Company” achieved.

The second spin-off series to “Man About the House” saw Tripp open his own restaurant named “Robin’s Nest.” Running for six series, “Robin’s Nest” was televised from 11 Jan. 1977 to 31 March 1981.

Loosely based on “Robin’s Nest” was the American situation comedy “Three’s a Crowd.” Like “Robin’s Nest” in respect to “Man About the House,” “Three’s a Crowd” was a spin-off from “Three’s Company.”

The first episode of “Three’s a Crowd aired on ABC one week after the final episode of “Three’s Company.”

Each of the six productions mentioned in this article were popular on their own respective sides of the pond.