GLASGOW, UNITED KINGDOM - SEPTEMBER 16:  Scotland Office minister David Cairns walks out from the BBC Scotland building in Glasgow after resigning from the government on September 16, 2008 in Glasgow , Scotland. The Inverclyde MP is the first minister to resign since rebel MPs began calling for a leadership contest. Getty Images logo Getty Images 41 months ago

GLASGOW, UNITED KINGDOM - SEPTEMBER 16: Scotland Office minister David Cairns walks out from the BBC Scotland building in Glasgow after resigning from the government on September 16, 2008 in Glasgow , Scotland. The Inverclyde MP is the first minister to resign since rebel MPs began calling for a leadership contest.