Second saddle world. They have a really good selection. Worked great for loads of others I know but sadly had nothing to properly fit my ever changing nightmare of a horse (she's stumped numbers of other master saddlers so can hardly blame them)
I don't know exactly what area they cover, but I've had Juliette Lily (Mayfield Saddlery) and David Dyer out to mine. Horse seems happy with the saddle we ended up with, and both brought a good selection within my budget.
In theory take them in to sell on a commission basis (can't remember if it's 20% or 25%) However gave them one to sell when they were fitting a horse on the yard 2 years ago, not heard anything back and they ignore all attempts to contact them so wouldn't recommend for selling.