Always judge the gun, not the name.

There are some very fine guns with little known names, just as there are some quite 'ordinary' grade guns with 'top names' on them.

Quality is not the same as (monetary) value; Having a name such as Purdey, H&H, or Churchill on a boxlock will enhance value, but it will most likely have been made in Birmingham, and an identical quality gun from the same maker with a Birmingham name will cost less.