Off the subject a bit but safety is not at issue here because one of the mechanical safetys of the revolver/pistol is that it CANNOT fire unless the cylinder stop is engaged with the cylinder. It is only in this position, with the cylinder stop in the frame bridge (the part below the cylinder) protruding upwards, and engaging into the recess in the cylinder that the primer is aligned with the striker. There is a tiny amount of leeway here and this is catered for with a set of gauges called 'the pokering set'.
In short, regardless of the principal problem as pointed out by Patrick, the pistol is 'safe' by definition.
And Patrick is also absolutely correct about the length of throw of the hammer. On single action, (action hand cocked) the pistol fires off the trigger bent of the hammer and the hammer is at full throw. On double action firing (trigger rotates cylinder and fires weapon) the weapon is fired off the spring loaded CATCH, hammer and hammer does not reach full throw.
I hope that this is close enough to the Webley as I have only got a skeletonised Enfield handy to shake up the memory buds on my brain