...second the endorsement for westley richards' leather slings (made at the birmingham factory)...for a big bore double, the 2.0" sling in havana or london tan looks spectacular, imho...

What type of sling eyes does your rifle have? If you have the large holes as is typical english you should have a two inch with the leather thongs on each end. They tie on and are proper and quiet. Some people like the hook but it can scrath the blueing and stock, as can detachable swivels. The hooks are also Winchester and not English.

Why would you want a sling? Just have a trusted native carry you double. If he ever strays more than an arms reach away then give him the thrashing of a lifetime. For his benefit and your amusement

Thong ended slings are the way to go on a traditional English gun.