Sir Paul McCartney becomes a billionaire at 84: Beatles icon is named the world's third-richest musician behind Taylor Swift and Jay-Z

Sir Paul McCartney has become a billionaire at the age of 84.

The Beatles legend is worth a staggering $1.4billion, according to Forbes, making him the third-richest musician behind Swift with $2billion and Jay-Z with $2.8billion.

McCartney’s biggest money-spinner is his publishing company MPL Communications, which he launched in 1969 months before the Beatles broke up. The business accounts for nearly a quarter of a billion dollars of McCartney's total wealth.

The Beatles' record deal is famously said to have paid the group less than a penny per album sold, even at the height of Beatlemania.

Their publisher Dick James controlled the copyrights to the lyrics and melodies McCartney, John Lennon, Ringo Starr and George Harrison wrote, with McCartney referring to it as  'a slave contract', in a 2017 Forbes essay. 

By setting up MPL in 1969, the musician retained control of his solo-career publishing and master recordings, and he secured a bigger cut of the royalties.

MPL doesn't just manage McCartney's own catalogue of hits though, it also owns the copyright to a huge array of songs.

McCartney cannily snapped up the rights to artists like Buddy Holly's back catalogue, before the music catalogue boom sent valuations off the charts.

He also owns the copyright to Broadway musical scores including Grease, Annie and Guys and Dolls and Christmas classics including Baby, It's Cold Outside and It's Beginning to Look a Lot Like Christmas, meaning that every time a song is streamed or a theatre score is performed on a stage, he earns a cut. 

Elsewhere, McCartney gets 25 per cent of earnings from the Beatles' Apple Corps holding company, which generates $50million every year from streaming, vinyl and merchandise sales. 

McCartney also makes $10million per year based on his share of Beatles songwriting copyrights, which he legally fought for over the past two decades. 

He is also still earning into his eighties thanks to his world tours, most recently completing the 79-date Got Back tour. 

He also released his 20th solo studio album in May, The Boys Of Dungeon Lane which charted at number one in Belgium, Denmark, the Netherlands and the United Kingdom. 

The retrospective album is full of 'memory songs' about his youth and bandmates, with McCartney musing: 'I like to go over memories, because it brings me back to the time. It brings me back to the people.'

Away from music McCartney has invested in real estate across the globe and boasts an extensive art collection that includes paintings from Magritte and Picasso.

Meanwhile, the musician's early years is about to hit the big screens with Sam Mendes' biopics of each member of The Beatles. Paul Mescal is set to play Macca. 

Alongside Paul is Harris Dickinson (John Lennon), Barry Keoghan (Ringo Starr) and Joseph Quinn (George Harrison).

Speaking about how he helped train Paul, McCartney said: 'He came into this office and I thought, "Well, I'll show him how to do Blackbird". So I picked up the guitar and started playing... and he played along exactly! I think he knew it better than I did!

'It was amazing how studied and how well-educated he was about me. So, yeah, I thought, OK, I'll leave you to it.'