File photo dated 25/6/2011 of Prime Minister David Cameron and Scottish First Minister Alex Salmond. The UK and Scottish governments were on a constitutional collision course today over proposals for a referendum on independence. PRESS ASSOCIATION Photo. Issue date: Wednesday January 11, 2012. Salmond has accused Westminster of trying to interfere in plans for the controversial poll. See PA story POLITICS Salmond. Photo credit should read: Andrew Milligan/PA Wire