Once lampooned by Australia as "single entendre comedy", Are You Being Served? was a situation comedy about the goings-on at the fictional "Grace Brothers" department store in London.
It was ostensibly a vehicle to showcase Trevor Bannister, a young and up and coming comedian - who played the most junior member of staff, "Mr. Lucas".
At the beginning of the series it was established that for reasons of economy, the "Gentlemen's Ready to Wear" and "Ladies' Clothing" departments were going to have to share a floor with each other, leading to tensions between the cantankerous and absent minded head of the men's wear department, "Mr. Grainger", and the pretentious, punk-hair-colored matron of the women's department, "Mrs. Slocombe" (Betty Slocombe, maiden name "Rachel Yiddle", actual full name "Mary Elizabeth Jennifer Rachel Avergaveny Yiddle Slocombe") played by the inimitable Mollie Sugden.
Mr. Grainger's department recently took on "young Mr. Lucas" to serve as junior salesman, with "Mr. Humphries" (Wilberforce Claiborne Humphries) rounding out the right hand side of Grace Brothers. Mr. Humphries was insanely camp and flamboyantly gay (though it was never actually revealed he was gay, such was extremely strongly hinted at throughout the series), practically gliding across the floor as he moved. His camp persona, occasional appearance in rollers or packing for an evening out (with a sailor, or the Scouts) and his penchant for switching between attempted butch and simpering camp "(baritone): MEN'S WEAR.... (high pitched camp), ooh 'allo, mother!" annoyed the gay community at the time intensely, saying that the character was an offensive stereotype. The network was uncomfortable with the character as well and wanted it written out: at the beginning there were vague jokes about Mr. Humphries needing "therapy" and men nervous about him taking their "inside leg" - but as John Inman brought the character to ever more theatrical camp - the powers that be wanted him gone, or the show gone. The writers and producers stood behind Inman and stuck to their guns - rode out the anger on all sides - and decades later he's one of the most celebrated and loved "television gays".
On the other side was Wendy Richards as "Miss Brahms", who was brought in not only for her strong East End accent but her legs and "charm". As the series went on she was more and more made up - not only because of age but because her boyfriend at the time was physically abusive and she would show up to the studio with black eyes and bruises the makeup staff would be forced to try and hide.
Refereeing between the two was Frank Thornton, the floor walker "Captain Peacock". Ramrod straight, ex-military, always in a city suit wearing a carnation - and with a eye-bagged bug-eyed face that could be brought upon to give an incredulous stare of outrage (which they relied on, often). There was considerable tension between the two departments at the beginning of the show, stoked even further by the constant sarcastic remarks about Mrs. Slocombe by Mr. Lucas, but as time moved on Peacock became almost a fellow conspirator as both sides of the floor had to gang up against the vicissitudes of management and the ambient hassles of the late 1970s.
Rounding out the cast was middle management, as presented by the dim-witted, slow-on-the-uptake "Mr. Rumbold", the prodigiously-eared and gap-toothed Nicholas Smith, who parlayed his odd looks into comedy, being referred to many a time as "jug ears" throughout the series. Also was Arthur English as the maintenance staff, in a brown lab-coat type janitorial uniform. He was usually called upon to represent the lower classes, or to bring some kind of prop.
There were three main sources of humor:
The first was the use of sexual innuendo and double entendres, but done with such unsubtlety as to make ABC make the joke about "single entendre". Mollie Sugden made multiple remarks about "her pussy" (if I don't get home and give it a stroke, it'll end up shredding me curtains in the night) - the eventual punchline to this being a Qantas ad in which she appeared with a similarly dyed cat. Broken inflatable devices sounding like passing gas, vague references to homosexual attraction and "hasn't she got a lovely pear" (stares at breasts) "yes, I should say she has." One classic line had the two women in the department complaining about each other - Miss Brahms objecting to Mrs. Slocombe confiscating her padded bra, and Mrs. Slocombe objecting to Miss Brahms saying the underwear ordered for the department was too cheap and tacky even for her. "Quit nicking my knockers!" "Quit knocking my knickers!"
"Young" Mr. Grace, played by a elderly, half-deaf man with a fading aging voice - was always accompanied by a nurse, giving the show the opportunity to have a rotating carousel of stacked, scantily dressed nurses in the "Carry On" vein, as well as having the sight gag of needing even more medical attention when she bent over or somehow inadvertently brushing him with a giant breast.
The second was prop gags: usually Arthur English would bring up some kind of display that some company had sent to spur sales: either a ludicrous concept (a dummy wearing a new kind of bra whose breasts lit up) or something that went comically awry ("Aw'l aff to tike it daaahn stairs an givit an adjustment!"). These were slowly phased out as the series went on, being error-prone and expensive to make.
The third was a sort of class-based comedy that took over, involving the politics of the day eventually. Mrs. Slocombe took on airs and spoke in a received English accent in public, reverting to a Northern drawl in private, or when angry. Pulling rank was a common tactic on the floor, with them obsessing over who got how many ruffles on their blouse given a certain number of years of service - that sort of thing. Later, as the members of staff tried to rub two five pence pieces together to make 20p, the lower class unionized janitorial staff would wave their larger pay packets in their faces - laughing at the whole notion of their supposed superiority. When Mr. Grainger was replaced (the actor was getting on in years) one plot point with a new head of department hire was that he had served with Captain Peacock in the army, and knew full well that Peacock had only ever achieved the rank of corporal. Seems like a small detail, but that revelation would have caused his career significant damage, and it made his previous puffery a complete fraud.
The show also moved into topical humor as the strikes and economic malaise of the 1970s dragged on. Sales were always slipping, the management were always thinking up some new hair-brained scheme (surveillance cameras, making the staff wear their own clothes like they do in America, etc.) Transport became unreliable as strikes bit hard, and in one instance the entire staff had to bed down with camping supplies in the department.
Trevor Bannister moved on and was replaced with young Mr. Spooner, who they wrote out of the series in the end as leaving to pursue a rock singing career (the gag being that the actor actually had had a Top 20 hit in the charts and had moved into acting from singing.) Mr. Grainger was of course, retired and replaced with a couple of actors. Arthur English retired as well due to ill health and was replaced by a more abrasive cockney.
Also as time moved on, they went from the earlier gags to often engaging in "musical episodes" - anchored by Nicholas Smith's piano playing ability and the opportunity to showcase Mr. Humphries as a high-strung diva. The gist of these episodes involved finding a reason to have the entire cast learn some kind of song and dance routine (once, it was because they had to entertain the children at the staff's family party, another, as a tribute to Young Mr. Grace) instead of being funny. By the time the series neared its end it was starting to wear out its welcome, but by the time it ended it had become an institution. It was later revived with a spiritual successor, "Grace and Favor" - in which a partial subset of the cast inherit an old folks' home in lieu of their pension (because of mismanagement by the Grace Brothers executive board) and have to eke out a living with it in their old age.
But they'd left a legacy of characters - the flighty Mr. Humphries in his flamboyant clothing, the inimitable and indomitable Mrs. Slocombe, and the sarcastic, sly-smoking Mr. Lucas. They also left a legacy of catchphrases - "My pussy....", "...and I am unanimous in that!", "Are you free?", "Daft boy!", and of course... "young Mr Grace?" "Old Mr. Grace doesn't get out much."
EDIT: Kudos to user Hazelnut whose comment on this caps it perfectly: Young Mr. Grace's catchphrase - "You've all done very well...!"