The 52-year-old U2 singer famously owns 2.3 percent of the shares in Facebook through his private equity firm, Elevation Partners, which it bought for $90 million in 2009 and now stands to make a very, very handsome return.

Given the social media company is currently valued at over $100 billion, this makes Bono's share worth over $1.5 billion (£940 million) and puts him well above McCartney, who is currently the world's richest rock star with a fortune of £665 million, according to Britain’s NME which knows such things.

Facebook is set to float on the stock exchange and all its early investors are set to earn huge amounts of money from the flotation, with the Irish singer among them. But you sort of have to wonder how meaningful even that gargantuan amount is to Bono, who earned more money on his band’s record-shattering 360° Tour than… oh I dunno, the 2010 GDP of Austria?

Add that to his stockpiles of cash from previous tours and records, iPod advertisements and forays into smash Broadway productions and it presumably all becomes rather abstract although the hangars needed to house it all likely offer some perspective.

In other U2 news, NME also reports that the band is rumoured to be working on new material with One Direction's songwriter, Swedish pop svengali Carl Falk, who penned the boyband's “What Makes You Beautiful.”

A source is quoted as saying: "The band are back in the studio getting a feel for new material after the last album No Line On The Horizon. Will.i.am had a credit on that and they are looking to explore that direction further. They have been working with Danger Mouse and RedOne. They are excited about getting to work with Carl Falk."

Better buy another hangar.

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