But Mad Men saddled up for a sixth season in 2013, and the Sixties were its wellspring. Not the '60s; after all the show began in 1960. No, I mean the Sixties. The place where blissed-out people in kaftans mumble "peace man" as Jefferson Airplane's White Rabbit plays on the soundtrack; the place where GIs drop out of a helicopter in the jungles of Vietnam to Jimi Hendrix's rendition of All Along the Watchtower. The most tediously mythologised period of history outside, I'll wager, the 1920s.

As a child of the '70s, I was just a little intimidated by "the Sixties", eventually seeking refuge not in the modern day but to the era immediately preceding.

Anyway, the '60s, boring as it may be to say, was a time where virtually every Western nation embraced conservative politics, not leftist change. Some countries (Greece; Mexico; Czechoslovakia) got more repressive. It was the time when people still got married, and young, something like 23 for males and 21 for females. More young people looked like the Carpenters than the Grateful Dead. Popular entertainment (especially cinema) became less hokey, but if television was your main entertainment, it was lean pickings. Popular music expanded its horizons, but the Beatles were bested on the UK album charts, at least, by the soundtrack to The Sound of Music, and on the singers charts, by a crooner named Engelbert Humperdinck and an old-style comedian named Ken Dodd.

I was a little perturbed by Mad Men's rapid progress from the exotic and relatively unexplored world of 1960 to the shopworn world of 1967, and wrote an article – part warning, part pre-emptive surrender – for this very page last year.

A big aspect of Mad Men's appeal to me is not in the way it lets us cast easy judgment on antediluvian mores, but the way it gives us "old timey" people without "old timey" restrictions. Movies until the mid 1960s have a frustrating coyness about them. Mad Men is just as glamorous and unrealistic, but it lets us imagine what old time stars such as Cary Grant and Grace Kelly would be like if they didn't have to, err, beat around the bush. Mad Men is not always pretty; in fact it can be pretty vulgar; but what TV and cinema could not convey, except via allusion, in that era, is there. But in the late 60s the restrictions on dramatic portrayal in cinema collapse with the demise of the Hays Code. The division between us "real people" and characters collapses.

So what, though? After all, advertising people, like we notoriously louche and libidinous journalists, were not constrained by the morality of any particular time and social milieu, surely?

MM season six does have its "Peter Sellers in The Party" moment, but otherwise is generally free of the cliches on offer from the 1967 Summer of Love and 1968's Year of the Barricades.

The cliche goes if you remember the Sixties you weren't there, but this is a comforting sophistry. Much of what we think happened in the '60s really happened in the '70s - equal pay for men and women, for instance. The '60s were in reality a remarkably self-stabilising decade in the Western world. They "began with the end of Nixon [and] end with the beginning of Nixon", as one unlikely font of wisdom puts it: the contemporaneous sleevenotes of one of my treasured records of hits from the decade (20 Great Stars Perform 20 Great Hits Of The 60's [sic]) put it.

Look further, if you will, at the journey of Richard Milhous Nixon in the annals of Mad Men. In season one, the reliably Republican ad agency Sterling Cooper is pitching for the Nixon account, not the Kennedy one, for the 1960 presidential election. This conjures one of the earliest examples of the show delivering an in-joke for the modern audience:

Roger Sterling to Don Draper: Young, handsome, navy hero - it shouldn't be hard to convince America Dick Nixon is a winner.

Eight years on, as season six wraps up, Nixon finally looks like a winner in his quest for the White House, but Sterling Cooper's ambitions to be part of the political fray have long evaporated. There was a passing reference in season six to one of the head "creative", Stan Rizzo (Jay R. Ferguson) working on "Daisy". That was the celebrated 1964 television spot for President Lyndon Johnson's campaign, shown on only one night, that shows a little girl pulling petals from a daisy as the nuclear countdown is heard.

Meanwhile our guys have remained generally in the Republican camp (not the creative team; they were never there). I mean Bert, Roger and Don, the latter still defending police tactics as the rest of the cast look jaw-dropped at the violent repression of protests at the 1968 Democratic Party convention in Chicago. The protesters were throwing stones, Don tells his wife Megan (Jessica Pare). But Don eventually lets slip his feeling that the war in Vietnam is wrong.

But enough with the politics. What of our old friends? Poor Pete Campbell (Vincent Kartheiser), condemned to being the ugly "sister" to Don, the man he hates. Pete is belatedly reconciled to Don's luck and seemingly easy brilliance in season six, but he remains a shadow, the man who tries to emulate Don, but for whom nothing goes as smoothly as Don. Pete was a surprise breakout in season five, but he has a dismal season six, with horrible hairline to match. "You were a sour little boy and now you're a sour little man," admonishes his mother. "You were always unlovable." Poor Pete.

But then Don (Jon Hamm) is not making every post a winner either. He pitches and misses at times. The quest for an old soup ad leads to the proverbial Rietta Wallenda-sized misstep with the Chevy account. What happened to the man who only needs to get in a room with a client to conquer? His home life is no less chaotic than it was with first wife Betty (January Jones). But while she gets to snipe at him, from the commanding heights of the ex-wife, she is not completely inured to his charms. Close the door, Don, you'll let the bugs in.

The wit that gave us the Nixon quip is less frequently on the lips of Roger (John Slattery). To my dismay he has become less and less likeable. In season six, especially, he is a petty bastard, throwing out the guests at the funeral of his mother just because his ex-wife has brought her other half. Once upon a time it would have been enough for Roger to dispense with the "old shellback" with a telling quip ... like "old shellback"). In the "Peter Sellers" party scene Roger goads a diminutive ex-colleague. His humour is a low blow, and he deserves that hit to a tender region.

I used to think that Don was the grump and Roger the debonair charmer, full of "Sterling's Gold", the wisdom of "when God closes a door, he opens a dress" (I am aware that it is this sort of thing that makes Mad Men anathema to a section of curious viewers). Anyway, Roger blew it badly with Megan's mother Marie (Julia Ormond) in season five, and he offers little in the way of joy or wit in season six.

This was the season where Don has become reverent about love. The ending of his affair with Sylvia Rosen (Linda Cardellini) leaves him vulnerable. She turns the emotional tables on him after he made her hole up in a hotel room without so much as a paperback to while away the hours of waiting for him.

Back to season one again. In the very first episode Don tells Rachel Menken (Maggie Siff):

By love you mean big lightning bolts to the heart, where you can't eat and you can't work, and you just run off and get married and make babies. The reason you haven't felt it is because it doesn't exist. What you call love was invented by guys like me ... to sell nylons.

Eight years on, and Don is complaining that the word "love" has been debauched by the culture. The light he sees!

The status of gays has been an intriguing undercurrent over the seasons. In season three, Don discovers the orientation of illustrator Sal Romano (Bryan Batt), and does him the favour (I guess), of not being the "truth-teller" that Campbell was to him. When Sal relates the unwelcome advances by Lucky Strike's Lee Garner jnr (a man who is the subject of an alarming revelation by Roger in season six), Don makes a sneering reference to "you people". Later, Duck Phillips (Mark Moses), propositioning Peggy for a hotel "nooner", dismisses colleagues Kurt and Smitty as "a pair of homos." That was the morning of the day JFK is killed. And five years later, Campbell describes his mother's gay carer as a degenerate. Well, the Stonewall riots are but seven months away from the end of season six. No luck for girls who like girls though. There's a great scene between Megan and a fellow soapie actress who wants to know her better.

Change for the biggest "minority" is coming too. Mad Men is one heck of a show about women. I used to think of the "three graces" as representing the stages of women's advancement. Betty: the model (no pun intended) of the past. Joan (Christina Hendricks): the present (an extremely elongated present). Peggy (Elisabeth Moss): the future. You can take the analogy a certain distance, but no further. Anyway Betty is happy with life now, and it shows.

And so on to random observations:

Mad Men is always good for a shock tactic, such as the Draper family leaving their litter on the picnic ground, or Betty's memorable warning to the children, one wearing a plastic bag on her head, not to make a mess. Season six's shock tactics come early when Betty tells husband Henry Francis (Christopher Stanley) she will help him rape a 15-year-old houseguest Sandy (Kerris Lilla Dorsey). Now that's a channel-changer!

Random observation 2: Mad Men makes a fair fist of displaying the world of work. That may be its legacy, a reminder of how central work is to our lives.

Random observation 3: Everyone loves finding anachronisms in Mad Men. My offering would be Pete telling Bob Benson (James Wolk) his mother "has dementia". The term, now out of favour, would have been "has gone senile".

Random observation 4: Thank you and amen, for the way the show takes down the self-righteous. A reprise of the "hippies versus The Man" skirmish from season one happens in season six. In Babylon, season one, episode six, Don, "seeing" the free-spirited Midge in Greenwich Village, wins one for the old ways. "How do you sleep at night?” a beatnik challenges him at a poetry reading. Don: “On a bed made of money.” The counter-culture is on stronger ground in 1968, but tribune of the old ways Jim Cutler (Harry Hamlin) is a points-winner in his stoush with Michael Ginsberg (Ben Feldman) the "creative" who calls him a fascist and suggests he get into the Vietnam War body-bag business. "I hate hypocrites like hippies who cash cheques from Dow Chemical and General Motors" responds the man in the grey suit. Cutler needs more opportunities to shine. Furthermore, there's Peggy's boyfriend Abe Drexler (Charlie Hofheimer) as the blinkered white liberal who ultimately decides she is the enemy, not the people in the neighbourhood thugs, muggers and rock throwers.

Random observation 5: I will digress, possibly digress on a digression, to say that Mad Men often hints at certain things and fails to follow through. Remember the first episode, when the middle-ranking Mad Men men hit the strip club? The scene is notable for the paunch on the stripper, a mild shock tactic perhaps, certainly clever nod to a time when '60s bodies were by no means as toned as they are now expected to be, at least for people who make a living out of showing theirs. How is it that this form of "gentlemen's entertainment" is hardly mentioned again, with small exceptions, for another five seasons, when Roger, in LA with Don, suggests they head out to Sunset Strip (no pun intended) to "watch a girl dance in a cage".

(Speaking of Roger, what happened to the recovering heart-attack patient? He seems to be getting more hedonistic, not less.)

Random observation 7: The portraits of JFK hanging in people's homes are a reflection of the time; intriguingly there is a giant poster of Moshe Dayan in Stan's bedroom. It's a poignant reminder of the time when the Left championed Israel.

Random observation 8: The incidental music is getting darker. David Carbonara's work cannot be praised highly enough. And the featured songs – well, whenever something by Sergio Mendes and Brasil 66 comes on, God is in the house. Going Out of My Head plays on the Admiral radio in Sylvia's kitchen as Don loiters outside her apartment. Someone give the music director a raise! A treat for music nerds: the original '30s version of Dream a Little Dream of Me playing in the brothel where Don lived as a boy. I only knew the Mamas and Papas' version; that quartet closes an episode of season six with Words of Love, a song that contains a gentle warning to our friends:

Words of love, so soft and tender

Won't win a girl's heart any more

If you love her then you must send her

Somewhere where she's never been before

Worn out phrases and longing gazes

Won't get you where you want to go, no

And I loved the reference to Mark Lindsay by Sally Draper's friend Julie, smitten by the sight of Sylvia Rosen's son Mitchell and comparing him to the teen idol. One day, (when this job is crowd-funded?), I'll write up an appreciation of the unjustly forgotten Mark Lindsay.

A little music trivia: Did anyone else make a musical link with these two incidents? The first, when a quack injects the Sterling Cooper backsides with a mystery energy supplement. I thought of the Beatles' Doctor Robert). The second, when one of NYC's finest asks Abe what sort of shoes his assailant wore. The cop reckons the suspect is black or Puerto Rican and says the shoes will help identify him. Remember the "PR shoes" in the Velvet Underground's Waiting for the Man? The song refers to the footwear worn by Puerto Rican immigrants at the time.

Rising crime is a subtext to season six. As much as the Vietnam War and the assassinations of the Kennedys and Martin Luther King, this was the cause of the souring of the general mood in the late 1960s. In the late 1960s, the biggest US cities are battling a huge rise in crime. Those incessant sirens are spoiling the ambience of New York. In 1969 singer-songwriter Laura Nyro could ride a horse and carriage to night recording sessions. By 1976 it's Taxi Driver town. The shift is indicated by those sirens outside (as we know Mad Men is 99.9 per cent or thereabouts interiors) and in the 12th episode, a Nixon campaign ad targeting the crime wave.

Mad Men season six is likely to climax with the advent of the Nixon presidency. A seventh, final, season, is promised. Then we must form a circle and cling to each other.

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Mark Sawyer is a Herald journalist who has written articles on Mad Men since 2009, beginning with Before Mad Men there was the Apartment (November 24, 2009).