Mind you, I don't suppose everything that's labelled lamb is quite as youthful as it pretends to be. I expect we eat plenty of mutton in disguise- and especially in pies and ready meals and such. That phrase "mutton dressed up as lamb" didn't gain currency without a reason.
A year or two back Prince Charles figureheaded a campaign to reinstate mutton. He gave mutton parties and was filmed munching on the stuff and going "Mmmmmm, delicious", but I don't think it had any effect. Leastways I've yet to see mutton- advertised as such- on the butchers counters in the shops round here.
With one important exception. The Asian owned supermarkets sell it unashamedly. They call it sheep. We bought some sheep last week and put it in the slow cooker and served it with mushrooms and rice and it was perfectly fine, not tough at all and- to be honest- if I hadn't have been in on the secret I wouldn't have guessed I wasn't eating lamb.
Oh, we also put a sprinkle of coriander on top. I love coriander.