FWIW (probably not much, if anything), I own a Bernardelli Gamecock 20 gauge with 25 inch barrels. It weighs no more than 6 pounds.
For a number of years, it was the only shotgun I owned and I shot birds, hunted deer with slugs (didn't shoot both barrels anywhere near the same point of aim) and shot skeet with it. Not the perfect tool for any of those tasks, but it worked fine as long as I practiced with it regularly. It was only after I began shooting true target guns that I realized how light and whippy the Gamecock was. I have some trouble with it now, but that's a result of having a number of longer, heavier, target style shotguns with weight forward that make it much harder to stop the gun. I'm out of practice with the little lightweight.
I suspect that a British shooter using nothing but a Churchill 25 inch game gun got very good with it and shot enough to overcome whatever inherent limitations that exist in a short, lightweight gun.
By the way, the Bernardelli carries like a wand and is still a great poke and shoot shotgun for the grouse woods.
