I started full time work as a teenager in 1972, in an office of an insurance company based in an old country mansion. It had a proper dining room (not a canteen) where lunch was served, usually a roast, a home-made pie, or fish and chips (no foreign food like pasta or curry). The 'senior' person heading each table served the other seven staff and you ate what you were given. I'd been a picky child and my whims indulged at home, but I learned to eat all my vegetables in that dining room because as a junior I'd have been far too embarrassed to risk being berated by an older person if I hadn't. Morning coffee and afternoon tea came around on a trolley.
The happily married guy who worked alone in the post/stationery room had a comprehensive stash of porn magazines which he ran as a sort of lending library. I read a year's supply of 'Forum' magazine from his collection, and most informative they were too. Weirdly it didn't even seem creepy. He didn't scare anyone.
The manager relaxed the rules on females wearing trousers during my time there, but said he had to draw the line at bare midriffs!
'The Computer' was an ICL behemoth the size of a car and it was fed punch cards peppered with tiny rectangular holes produced by the three key punch operators. Nobody had screens. We had stacks of pre-typed 'form letters' for routine correspondence, which we addressed and signed in fountain pen, we hand-wrote drafts of more complex letters which were vetted by the section head before being passed to the typists, who'd type it up (two sheets, using carbon paper), and type the address on the envelope too.
I trained as relief receptionist and learned to use the new PMBX switchboard, so modern and advanced compared to the one with wires and plugs which preceded it (I learned the PABX switchboard in my next job).
Smoking at the desk was the norm in all the offices I worked in until it was banned by law in 2007. At my last workplace the small number of smokers still lit up on the stroke of 5pm, right up to my leaving in 2017 - the bosses smoked so what they did, others did.
I hate office work but it certainly changed out of all recognition over the 45 years since I started, and the first one was the best by far.