How do I find the owner of a songs copyright?

I live in the UK. My friend is a singer and would like to cover the song ‘Ride On’ by Christie Moore for a demo CD and possibly to sell on the web. Having done a little bit of googling we thought the best way to find the copyright holder was to e-mail the artist’s manager (as listed under the UK & Europe inquiries on his website). It’s been over two months and she has not heard back, so which direction do you suggest we head now?

Wiki states his last two records as being released by Colombia, however he is not listed on their website.