I am a long time brewer of cider and 8-10 years ago when I started you could buy the concentrated cider cans at Wine Kits and most any other brew place but slowly fewer and fewer places stocked them and the last place in my city, London, who carried them said that John Bull went out of business and that they didn't know where else to get them from.
I've been looking all over the place and I can't for the life of me find where in this country or even in the US you can but the 2 litre concentrated apple.