According to Hipgnosis founder Merck Mercuriadis, the music he's bought is "more valuable than gold or oil". "These great, proven songs are very predictable and reliable in their income streams," he explains. "If you take a song like the Eurythmics' Sweet Dreams or Bon Jovi's Livin' On A Prayer, you're talking three to four decades of reliable income." He says hit songs are a stable investment because their revenue isn't affected by fluctuations in the economy.

Streaming changed that, he says, because previously passive consumers were willing to pay a monthly subscription. "Instead of the focus being that one in 350 people would actually pay for music, the focus is on all of them."

In fact, the campaign has been equally critical of both streaming providers and record labels - but Mercuriadis says people should focus first on increasing the global subscriber base of streaming services from 450 million to two billion by the end of the decade.  "Because if that becomes reality then the earnings of the songwriters will be very significant".

Over time, old media should become worth more as there is less and less of it in relative terms. People are buying vinyl knowing that the declining numbers of unplayed records will increase the value of their investment, further inflating vinyl sales numbers.