I notice that classical players hold the instrument almost vertical, because of the way a reed instrument works. But jazz players tend to be portrayed holding it more horizontal. But when I do this the sound is weaker because the reed is being blown at a different angle due to the classic clarinet embouchure.
I know many players favour the double lip embouchure and this allows the player to hold the instrument higher. So is that where it comes from, the new orleans jazz era?

Concerning condensation and buzzing, do you warm the mouthpiece up before playing? As a recorder player I know this is an important thing to do to avoid condensation building up and causing a muffled sound. On a clarinet it could be causing the buzzing sound I get after playing for a while. The way I see it, moisture builds up between the mpc and reed (both plastic) and with nowhere to go it sits there and affects the sound. It may be more of an issue if, like me, you use a synthetic reed. Might warming the mpc/ reed  up before playing help?

I can't see from pictures online how the leather tab attaches to the clarinet! My thumb rest has a ring at the top at right angles to the actual thumb rest, (looks like L )which is able to be moved up and down via a large screw .

A tune from the James Rae book I have.
I realised that when I played this before I was playing 3 notes to the bar! Oops. I practised it quite a few times with the metronome before making a recording.
https://youtu.be/8dNekjR03T8

I mentioned C clarinet on a Facebook group and came to the conclusion that they are frowned upon, poo pooed and generally derided, but why? Surely having a non transposing instrument makes a lot more sense, certainly to me. Anyone on here like them? And how much shorter in length is one compared to a Bb? I was wondering if its possible to get a very short barrel, converting my Bb to a C...

I was browsing Wikipedia about clarinets and I found a link to a video of Alphonse Pichou playing the rare Saxonette, basically a Bb clarinet with upturned bell.

https://youtu.be/_ftr_knt4D8

Inspired by Trent Hamilton's numerous brass videos in which he plays Carnival of Venice a lot I thought I'd try a bit of it on clarinet.
By jove it works, though you can forget the fast passages...😜
https://youtu.be/sNzK7sxKvss