The Dublin-brewed version of Guinness Foreign Extra Stout is still available in Sainsbury's and I was able to do a comparative tasting with the Nigerian version discussed earlier.
It's a remarkably different beer. While it's no longer brewed in the traditional manner of blending "stale" stout with fresh, it still has a touch -- though more muted -- of "horse blanket" on the nose, along with roasted grain, a vinous fruit note and bitter hop resins. The palate is intensely bitter from the roast and hops, with dark, burnt fruit, while the long, complex finish has roast, hops, liquorice and fruitiness akin to over-ripe bananas.
Sainsbury's has a good beer offering, including Brakspear Triple and Fuller's 1845 and Vintage Ale -- though as these are southern beers they may not be available nationwide. But worth checking.