York made the Holton (32" x 19") BB-flats' and E-flats' bells and bows...

[bloke]

@Robson

When I fired up my laptop (I do repairs, and have to submit nice letterhead-lookin' quotes to schools) this morning (just now), I edited my response to your post with a couple of pictures w/comments...

...This was after you responded to my response (opinions/observations) to your inquiry...so I'm just tagging you to let you know about the added pictures.

Now that my laptop is fired up (much larger screen), I'm looking at @lost's avatar...
I'm sure that's a top-action 6/4 York B-flat (correct?) The large upper bow width appears identical to the EARLY Holton 6/4 large top bows (contrasted with the LATER Holton model 34X - actually made by Holton) narrower-width large top 6/4 bows.

When straightening out HOLTON-made (narrower) 34X-era 6/4 top bows, I have to be PARTICULARLY CAREFUL, as (obviously) Holton relied far too much on belt-sanding to make the 34X (narrower) 6/4 top bows. In contrast, when I've repaired VERY OLD Holton and York (wider) 6/4 top bows, it's obvious that more craftsmanship (and less belt-sanding) was involved, and I don't have to be so very extremely gingerly, when repairing them.

[Robson]

As a trumpet player, I can assure that York used to make parts for other companies. Some of my friends are cornet collectors

I have a York cornet from 1906, Monarch model. What a Cornet!!!

[MiBrassFS]

.

[bloke]

You're only imagining that they play the same, because one is silver and that's going to be totally different.

[MiBrassFS]

.

[Yorkboy]

Mr X, a long-time and valuable employee of Mr Y, decides to take what he’s learned at Y’s company and start one of his own.

Mr X starts his new firm on a shoestring, and can only supply a small percentage of products that he wants to, so he goes to Mr Y, buys the items he is not set up to supply himself (yet), and puts his name on it (aka “stencil”).

After a while, Mr X makes enough money (or is able to interest investors) to tool up to build his own version of Mr Y’s product - however, since he learned all he knows at Mr Y’s firm, his product (intentionally or not) is heavily influenced by this. The items might not be exactly identical, but the influence is clearly there.

Plug in Mr A or Mr B, as this happened routinely during the heyday of band instrument manufacturing in this country.

Rinse and repeat as necessary.

[bloke]

yup...
The last gasp of Holton - the Harvey Phillips instruments - I'm convinced - we're made in the Holton factory, but they're nothing like those from decades earlier - as far as how they play.
(and they're probably are those who prefer the Harvey Phillips instruments to the earlier ones.)

...and I don't believe it has very much to do with the fact that Holton used their since-forever .665" tubing on those instruments vs the typical King paste-on .687" tubing.