Two-piece?  Three-piece?
If you trawl through the 'Talk Ivy' archives you'll find a poster dismissing - if memory serves me well - a three-piece suit (specifically in tweed, I seem to recall) as not Ivy League.  TRS politely but firmly told him he was wrong.  Speaking for myself, I loved the three-piece tweed Brooks Brothers suit I briefly wore and thought it Old School Ivy with knobs on.  I felt like a Republican politician during the Eisenhower years or a staid adviser to young Senator Kennedy.  I suspect a regimental-style tie accompanied it in those days (2009); certainly cordovan wingtips.

Come to think of it, the shirt wasn't all that crisp.

It's an item of clothing that has fallen away as a wardrobe staple.  I wonder what posters like Uncle Ian and KingstonIan think of that. 
Not that long ago, doing a bit of research on English menswear retailers in the high street, I chanced upon the claim that the average English male once bought a new suit about every two years.  This I find difficult to believe.
My first adult suit came from Harry Fenton in 1977.  An older friend, a former Mod, assured me that the wearing of a suit was a guaranteed passport to sexual nirvana.  I'm sure he didn't mean to take the piss but I may as well have taken the £70 it cost and handed it out on street corners.  The wearing of that suit did not make me look like Cary Grant or Sean Connery.

I bought at least five suits on Ebay, only two of which turned out to be truly satisfactory.  Not something I'd recommend or would do myself again but, in those days, Ebay Com. was relatively easy to deal with.  Then American sellers must have decided they'd all like second homes in Malibu and began charging absurd rates for shipping.  It's the same on ABE with books.  Now, since leaving the EU, some of our continental friends are also trying it on a touch.

What did Mick Jagger do? 
I find the idea of wearing a suit with sneakers pretty odd, although I did wear a navy Brooks two-piece with loafers.

'What are those lines around your mouth, Mick?'

'They're laughter lines'.

'Nothing's that funny'.

The dustbin of history perhaps?

I always wore suits from Sunday Best(with short trousers) to work. I could buy off the peg with a reasonable fit.

I felt comfortable in a suit, though the Sunday Best was only worn for a few hours and then changed out of.

I never understood the people who resented having to dress for work. I thought they were lucky not getting their hands dirty.

English tailoring in a suit looks better provided you are in reasonable shape. Natural shoulders is oversold and nipped in at the waist just looks so much better.

I do have Ivy jackets - but no Ivy suit. I still wear a suit if I go up town - but not locally. I am not sure I am in any hurry to buy a new suit either.

At the Oval yesterday I wore a blazer - an English one with metal buttons - not the Hardy and Johnson one with plain buttons. Polo shirt and navy merino v neck. Khakis and astorflex desert boots. Most were wearing sports apparel though there was an occasional Panama hat that looked pretty good. This was in the case in the stands and also the members area where I met up with pals. You can spot the cricket types when you get off at Vauxhall station. The same with beer festivals though the cricketers are usually in better shape and there are fewer t shirts

I enjoyed wearing my Ralph suits to work. they were an Anglo-American hybrid.
Natural shoulders but darted. Their tailors would then create additional waist suppression for that classic v look.
At the time the suits were made by Cornealani in Italy but the fabrics were very American in flavour.
I favoured a 3/2 soft roll on the coat, ideally with a ticket pocket, with flat front trousers, side adjustors and taper to 15" bottoms.

I hated wearing formal shoes and preferred loafers with my suits, especially tassels. I felt that was more American.

The late Charlie Watts, by far the coolest of that appalling mob, wore nice suits, didn't he?  Hadn't some of them belonged to the Duke Of Windsor?  I bet Charlie wore proper shoes or bench-made boots.

Off-topic but I paid around £5.50 to Harvey Goldsmith in the blazing summer of 1976 to sit in a field with a lot of stinking hippies for the dubious pleasure of being kept waiting hour upon hour by Jagger and his cronies.  They were sipping champagne backstage with Jack, Anjelica and various other fuckwits.  Now, if they gave a free concert in the meadow outside my house I'd draw the blinds, reach for my ear-plugs and wait for it all to fade and pass.  Rock music is the biggest lot of fucking cack ever foisted upon a gullible public.  Full marks to Woody Allen for stating publicly how much he hated it all and for digging cool cats like Alphonse Picou.

Mmm - well obviously a formal wool suit would look odd with sneakers.  As I thought I had made clear, I was referring to unstructured suits made from cotton, corduroy, linen etc which are already on the on the casual end of the spectrum to begin with. I cited Mick Jagger as someone who had done this style to good effect, naturally not in an Ivy way and of course not in a way that any of the venerable  Richmond Hill or Talk Ivy demigods would approve of either. But it is a cool look when done well and probably the future of suits for now.

In fact I only mentioned Mick Jagger in the context of wearing suits in a relaxed manner, not putting him up as someone who will be seen in future millennia as an artiste who made an indelible.mark on the history of music, to be be mentioned in the same breath as Beethoven or Mozart, no not at all. Some of the Stones early hits, songs we all probably grew up with, stick in my mind. But having looked through their discography, the last song they recorded that that I can remember is Start Me Up from 1981. Since then anything new I've heard from them always seems to sound more or less the same. A winning formula, are far as their fans are concerned anyway, churned out for forty years, who can blame them? I'm afraid if I was given tickets for one of their stadium concerts I would look for someone to give them away to.