Carling, the UK's biggest selling lager, is to sponsor the Scottish football teams Celtic and Rangers, also known as The Old Firm, to the tune of £12m, commencing on July 1st 2003 and lasting three years.   Carling is already one of the football's biggest sponsors in the UK, having backed the Carling Premiership for nine years (1992-2000).  Carling also has existing partnership deals with clubs such as Arsenal, Tottenham Hotspur, Leeds United, Sunderland AFC, Aston Villa, West Bromwich Albion, Blackburn Rovers and Wolverhampton Wanderers.