Not many people are going to agree with this, given the legendary classic rock bands we have produced in this country, but here goes! Anyway, it just so happens that my favourite two albums by any British artists EVER both happen land on the letter "K".
King Swamp's self-titled debut is exceptional in every way. Some superb 80s rock but mixed up with an edge of something harder and lyrically fantastic. Take this from "Year Zero":-
Year Zero and I'm back in the field.
Demolishing history for a new regime.
What were our virtues are now our sins.
The bad move out and the worse move in.
The guitars, the way some of the lyrics are mixed with some Lousiana mythos and the occasional use of dobro put this in my all-time top 5. Check it out if you don't know them
The other probably won't need an introduction, but despite the fact that many don't like them, Kula Shaker's debut K is a fantastic piece of 60s rock somehow released in the 90s. Some dynamite guitar, epic Hamoind Organ and a nice mix of Indian instruments knocks the socks off anything Oasis and Blur were putting out around the same time.
Also, my 3rd favourite album by a British band could well be classed as a "K", but I categorise by surnames, so I'll leave that one for now.