On the other side of the pop music spectrum in 1977 from Fleetwood Mac would have been the Sex Pistols. Punk wasn’t exactly invented by the Sex Pistols – Iggy Pop and later The Ramones were already there – but they captured the spirit of the moment and made a lot of noise.
The UK was declining rapidly at this point and social strife was a serious problem. Youth unemployment was high, extremist groups were parading around gathering supporters and there was very little hope for a generation. Thatcher’s assault of labor had not yet started, nor had her market liberalization efforts begun.
Those policies, much like the deregulation led by Republicans in the US during the Reagan years, would give a false sense of prosperity and advancement that would begin imploding again three decades later.
Love them or hate them (I’m in the love them camp), the Sex Pistols were an abrupt change of pace in the music industry.