Sir Paul McCartney's song 'Who Cares' was inspired by Taylor Swift's fans.

The 76-year-old music legend has revealed the track on his new 'Egypt Station' is about the cruelty of cyber bullying and when he was penning the lyrics, he imagined asking the 28-year-old pop star's fanbase - known as Swifties - if they'd ever had to face trolls online.

In an interview with BBC Music, he said: ''I was actually thinking about Taylor Swift and her relationship to her young fans and how it's sort of a sisterly thing.

''And I was imagining talking to one of these young fans and saying, 'Have you ever been bullied? Do you get bullied?'

''Then I say, 'Who cares about the idiots? Who cares about all this? Who cares about you? Well ... I do.'''

Meanwhile, the Beatles star previously admitted that he chose to make a concept album because he doesn't think he can compete with the likes of the 'Shake It Off' hitmaker and Beyonce.

Macca went down the old-fashioned route of giving his fans a record which takes them on a journey on his 17th solo LP like his own band did with 1966's 'Sgt. Pepper's Lonely Hearts Club Band' and their peers Pink Floyd did on 1979's 'The Wall' and 1983's 'The Final Cut', as he prefers the format to a ''collection of singles'' which many pop stars put out these days.

He said: ''These days you have the big stars like Beyoncé, Taylor Swift and Kendrick Lamar, particularly the first two, their songs are a collection of singles.

''They are all great commercial tracks but it doesn't roll through like a Pink Floyd album used to, or a Fleetwood Mac album.''

Quipping that he can't rival with 'Delicate' hitmaker Taylor's legs, he continued: ''So I thought, well, I can't compete with that Taylor Swift thing, she's got better legs than me!''