I saw Laurel Aitken live in Nottingham in around 1998. He put on a pretty good show (no surprise).

No, pork pie is the correct term for any flat crown. Except maybe for boaters.

They usually have narrow brims but they can also be a bit wider brim or pretty stingy ones.

The ultra small brim hats, Trilby, Pork Pie etc … were nicknamed Blue Beat hats in the UK. Some of them were Homburg hats with a cut off brim. That’s a stiff hat. Not nice.

'Working Girl'.  Watched it last night.  A feelgood movie from 1988, featuring the yummy Melanie Griffith and Harrison Ford wearing a cracking green scarf (not especially 'Ivy', I grant you but still nice) and glimpsed in a plain-looking sweatshirt.  Elsewhere, re male clothing, where would the suits, shirts, shoes and ties have come from in Manhattan circa 1987? 
Mike Nichols again.  A great, not prolific, director.

I got a pair of Italian-made Donegal tweed trousers from JS a few years back. Wouldn't have been a first choice, but were knocked down to clear so I gave them a shot. Turned out to be lovely trousers, and indeed pair well with soft denim or chambray shirts. Can only be worn a day or so without pressing though, or else they slouch into a shapeless mass.

TV instead.  Having watched the first two series of 'Hill Street Blues' (Alvey and Yuca are also keen), we found it difficult to buy 3 and 4 so have, for the time being, switched to 'NYPD Blue'.  We used to catch it late-night back in 1997 (I'd guess) when the youngest daughter was due her midnight bottle. 
As Yuca pointed out elsewhere, Ray in 'Hill Street Blues' may well be sporting Brooks button-downs.  Henry looked pretty Ivy to me, at least in some respects, with his bow ties and sleeveless jumpers. 
Now, in the first few episodes of 'NYPD Blue' we have a young Jewish lawyer who has the hots (perfectly understandably) for Kelly's estranged wife.  Good glasses, button-down...  but is it Ivy/Preppie/neither?  I think it may be a touch too neat (but, then, he is a professional).  Where would a guy like that be buying his clothes in New York in the mid-90s?

More full-on Ivy or Prep - from what we see of him - rather cool black actor, Clifton Powell, playing an architectural student.  Crew neck with (probably) button-down beneath, something a little more sporty later on.  Good spectacles, too.
Detective Medavoy in what could be a pink Brooks button-down.

I wish we could get The Weejun back on here.

I’m not sure if it’s been mentioned here before, but we watched A Single Man last night. The central character, played by Colin Firth, is an Englishman working as a college professor in 1962 L.A. The theme is a gay chappie grieving over the death of his long term partner, but there’s nothing explicit on view that might cause a committed hetero to hit fast forward or go out to make a cup of tea. Firth does wear what appears to be a tab collar and a natural shoulder suit in much of the film but he’s not overtly Ivy. Naturally he’s ideal for the eternal role of an impeccably mannered Englishman not quite fitting in with the easy going nature of American society. His students outfits are interesting in the campus scenes but the overall pleasure of the movie are the sets, the houses, the cars and the recreation of living near the beach in 1960s Los Angeles. It’s available free on IDMB which we found on our smart TV recently.

As for gayness, I'm not bothered.  Some of my best friends etc. etc.  But Woke I do not do, not for anyone. 
I feel enormous sympathy for some of the black actors: 'FFS, I'm going to be playing some crack-addict dirtbag again?  Get the fuck outta here'.
'But, honey, think of the pay check'.
'Uh...  okay...'

Signs on dotted line.

Really surprised you're not loving NYPD Blue as it was created by Steve Bochco. I remember back in the day being addicted to it.

It also has too strong a whiff of political correctness about it and is an unwelcome reminder of how the English have adopted modern American idioms.  'I'm good'.  'Reaching out'.  Somebody being on their fucking 'vaccine journey'.  'Hey!'  Along with this nonsense has come a lack of restraint, politeness, agreeing to disagree.

Last evening, Joel McCrea in Hitchcock's 'Foreign Correspondent' spent much of the movie wearing a button-down with no discernible roll to the collar.
Also Jerome Cowan, towards the end of 'Mr.Skeffington', wearing a rather nice sack suit (I assume: the movie is in black and white). 
Both films released 1942/43.

Currently on Sky Arts - ' Alfred Hitchcock Presents', I've watched 2 of these short dramas, recorded in 1955 in the USA, ropey stories but in the 1st episode the female lead wears a very volumous b/d , great collar roll, back pleat, wearing it around the trailer with no trousers, she looks rather attractive in it, looks like it's filmed on the west coast, some great shots of the coast, wonderful cars etc etc, worth a flick through I'd say,