Cover versions came thick and fast. Nancy Sinatra was first out of the blocks with a brassy version that reversed genders, repeating some of the tricks — for example, a slippery descending bass break — that arranger Billy Strange and producer Lee Hazlewood had used on Sinatra’s “These Boots Are Made for Walkin’”. Also in 1966, on Complete & Unbelievable — The Otis Redding Dictionary of Soul, the great singer took The Beatles’ vocal lines for a soulful walk. Mae West committed to tape one of the worst ever massacres of a Beatles song on the execrable Way Out West.

The genius of the “Day Tripper” riff is that it sounds good on almost any instrument: on sax and double bass for clever German duo Tok Tok Tok; barked out on brass for Geno Washington; and on piano for Sergio Mendes, who makes it sound like a Latin instrumental classic, with its hint of a Afro-Cuban montuno. Cuban percussionist and bandleader Mongo Santamaría cut at least two instrumental Latin versions. Yellow Magic Orchestra, one of many electronic acts championed by Rusty Egan, the “sonic architect” of the Blitz club (currently celebrated at London’s Design Museum), demonstrated how trippy the riff sounded on synthesisers (1979). Hamburg’s Punkles gave “Day Tripper” a convincing retrofit on Pistol, their album of punkified Beatles covers.

Also in Hamburg, musician and Beatles tour guide Stefanie Hempel, an authority on the group’s history, told me that “1965 was the great Beatles ‘riff’ year, with ‘I Feel Fine’, ‘Ticket to Ride’, etc, showing that they can also be the best ‘hard’ rock band if they want to.”

She points out the influence of Dylan on The Beatles at that time: “Leave the path of kitschy love songs, write in riddles, double meanings. Write about ‘emancipated’ women and put them down at the same time. They were always like sponges, soaking up everything.”

Some “Day Tripper” cover versions downplay the melodious riff. Jazz pianist Ramsey Lewis keeps it low in the mix on his groovy version (1966). James Taylor, on his album Flag (1979), teased listeners by hardly playing it at all, riding out the song with a stomping cocktail of percussion, sawing strings and falsetto vocals: Prince meets Talking Heads.

For sheer originality, it’s hard to beat José Feliciano’s passionate version of “Day Tripper”. Recorded live at the London Palladium in 1969, with flamenco-style acoustic guitar, double bass and percussion, it reaches an intensity that transforms the detached, satirical mood of the original into something ecstatic.