I think it's unlikely that they use the same recipe, accountants do tend to cause cost shrinkage, which has impacts on the quality of the product.

Bass used to use the union system of brewing, which created a consistent high quality product. But the bean counters didn't like it. However, the change destroyed the beer, which had previously been regarded as one of the best beers in the world with considerable market penetration. Now, I have no idea of any pub which sells it.

Most mass brewers will reduce malt content, especially of the more expensive malts and substitute rice, sugar and caramel where they can get away with it.

In this, the US brewers are more guilty. The freezing temperatures US consumers have been trained to expect beers to be served allows them to get away with considerable abuses of the quality process. Cold beer disguises all of that. The recent moves by Guinness to promote freezing cold dispense suggests they too are degrading their product.

keep to the Fen Causeway