Debate: Beggars founder Martin Mills last week revealed that some of his label's artists see significantly more revenue from streaming services than they do from radio play.

Popular music streaming site Spotify has now surpassed the four million paying subscriber mark worldwide and the service has more than 15 million active users.

However, the topic remains a hot potato: artists continue to complain about paltry royalties from the likes of Spotify - with some accusing labels of taking the ...