This is a professionally owned and maintained unlacquered yellow brass Paxman 40L (large) descant Bb/F.
It's the newer model design and is in good condition. I don't know if there is a single professional orchestra worldwide that doesn't have at least a few Paxman horns owned by the horn section.
You'll be able to approach the more difficult high horn repertoire with a horn like this.
The compression is 2.2 across five valves, which is very good.
Leather DB Gigbag is included.