Some excellent points! I'd never considered the Walton influence in some of the composers you mention, such as Orbon and Linde. I'll have to listen to Lovelock and Hughes again in light of your observation, too. Hughes' music is magnificent -- Dutton or Toccata should consider him!
While Hindemith certainly did influence Walton and Cooke greatly, I hear much more Hindemith than Walton in Cooke.
RR Bennett, Rutter, and Joubert -- definitely. I'd always thought of LeGallienne as more in the English pastoral style, but now that you mention it, there's certainly Walton there, too.
I haven't had a chance to listen to your work yet -- thanks for posting it, though!