There's a whole lot of Beatles, Wings, Badfinger and 10cc in them. Sophisticated British 70ies pop. They were a real band, but with interesting pedigrees: ex Bay City Roller (the singing bassist, he didn't want to do the teeny bop thing they were offered, so he left), top notch British session musicians. Some of them would end up in later incarnations of acts as diverse as Alan Parsons Project, 10cc, Al Stewart, Steve Harley & Cockney Rebel, Kate Bush and, yes, even Paul McCartney (the drummer Stuart Tosh). Though if you think about it: the common thread of all of them is "sophisticated British pop" and an affiliation with Alan Parsons as a producer.