By Zara Woodcock Paul McCartney once quoted lyrics from The Beatles at Russian President Vladimir Putin in the hopes he would release imprisoned Greenpeace activists. A new BBC documentary, called On Thin Ice: Putin V Greenpeace, will explore the campaigners and journalists on the Arctic Sunrise vessel who were charged with piracy in 2013 after a protest outside a floating oil rig in the Pechora Sea. Their charge was later downgraded to hooliganism After the 28 campaigners and two freelance journalists were detained, Sir Paul wrote a letter to the Russian president. The singer wrote: “Forty-fi…