Redhawk1: I forget the exact model number but I think those Webleys carry a 5" barrel. What you need to check for on those old warhorses is (1) cylinder rotational movement and (2) barrel condition.
I would normally expect the triggers to be horrendous in da and not to awful bad in sa. But, when you lock up the cylinder with the hammer cocked fully to the rear, see that they cylinder locks up tightly and in line with the barrel. Sometimes you may find a pawl broken or a cylinder lock worn down. If she locks up nice and tight that is good.
Next check the barrel. Many of those old wartime pieces may have used corrosive ammo and the barrel may be badly pitted. The barrel may also be leaded badly.
Also, check the overall lockup of the revolver. The top latch is not the strongest latching method in the world and you can get some 'shake' if she doesn't lock up tightly.
What you also need to remember is that there just aren't any spare parts available for those babies, so you either need to get a vg-excellent shape revolver or you may not be happy with whatcha got.
Lastly, slug the barrel to get the true bore diameter of that gun. I recall they took a nominal .360 dia 200 gn round nose bullet at right around 600'/sec - not very fast at all but those slugs would shoot right on through ya. The Brits felt they had the same field combat capability as the 455 Webley. HTH. Mikey.