Dennis Brain pretty much shaped french horn playing today! While I highly doubt there's any horn players out there who haven't heard of him, it's great that other instruments actually appreciate what a great musician he was.

He switched to an Alexander Bb horn actually - it was in the car when he crashed but I think it was Paxmans that restored it. Its on display either in RCM or RAM in London, I can't remember which.

There is a CD Box called "The Art of Dennis Brain". It contains 11 CDs with recordings of Dennis Brain (i.e. every recording there is). My teacher has it, so I was able to copy them, but I can't find it anywhere available. It was released by EMI and only in Japan. If you have any opportunity to buy it, do so! It is just excellent.

Dennis Brain was a fantastic Horn player.
However, I would not say he has shaped the french horn playing of today.

Mr. Brain has an embouchre few can explain. He stopped notes with his tongue (which is often taught today as a big NO NO.).
Dennis did break down some walls of solo horn playing.

Most teachers would tell you to do most things dififerent than Dennis Brain (embouchre, tongueing, type of instrument, and case of instrument). Dennis Brain played on an old piston valve horn for a long long time. And most of his instruments were pretty banged up, lots of dents.

So he did not shape todays players, but he did get us horn players on the solo circuit.

Speaking of big NO NO's...
It just occured to me that once a person becomes so good at playing horn, they should know the horn so well that you can make it do whatever they want in any manner, even if it's considered "wrong" (i.e. Mr. Brain stopping notes with his tongue). The main point of my pondering is that if doing such things is good for a seriously advanced horn player.

A lot of big NO NO's arent big no nos.
A lot of teachers have taught what they thought they were doing, when that's really not what they were doing at all.

There are sections of Phillip Farcas' book that are considered horn gospel only to find out many years later he said he shouldn't have written some of that. Or that he no longer believed that.

Doing bad things creates bad habits and everyone should avoid them. But some people get away with bad habits; sometimes because they used to be good. Example Dennis Brain really speaks out from the rest of the orchestra ( listen closely and often you will find he is sharp to the orchestra). It's a bad habit, and it's wrong, but he gets away with it.

A seriously goo dhorn player should play as best they can. They should always be trying to get the best sound and should always try to use proper technique.A good horn player should be setting an example for other horn players. But they should also be the ones trying new techniques to see if something works better; after all if ti is bad for you they are most likely able to recover from the side effects better than the rest of us.