Now I know I should have known this already and I am aware that I am exposing myself to ridicule from certain friends (yes, I'm referring to you Bad Fairy and Our Man in London), but I never realised that it was done as a homage to Elvis Presley's first album released in 1956. The black and white image; the design, layout and font; the special relationship of one man with his guitar...
In A Brief History of Album Covers, Jason Draper writes, "A mixture of punk, reggae and rockabilly, London Calling may well be to punk/ post punk music what Elvis Presley was to rock 'n' roll - a collection of influences wider than the genres the artists were recognized as spearheading."
Incidentally, another band to riff on the themes of the album cover is the phenomenally perennial Chumbawamba. Check out Tony Blair, sent to everyone on their UK mailing list in 1999.