In August 1966, the Beatles led their album “Revolver” with Harrison’s “Taxman,” a jagged riff that doubled as a fiscal protest. Britain’s top tax rates reached 95% on “unearned” income—or, as Harrison put it, “one for you, nineteen for me.” Success felt like punishment. The Beatles’ answer was financial engineering. It was meant to let them, good lads that they were, stay in the U.K.—rather than follow their unruly peers, the Rolling Stones, who fled to the South of France to record “Exile on Main Street” under similar tax pressures several years later. The Beatles’ attempt to protect their income stream would backfire twice, costing them control of their own songs, but it also helped shape one of today’s most coveted asset classes.