The University of Nottingham (which is most certainly British) has this in its style guide: "similarly, use the company is rather than the company are" [1]
The Economist (a publication of a British company) has a style guide that has this gem: "A government, a party, a company (whether Tesco or Marks and Spencer) and a partnership (Skidmore, Owings & Merrill) are all it and take a singular verb. So does a country, even if its name looks plural." [2]
[1] http://www.nottingham.ac.uk/public-affairs/uon-style-book/si...
[2] http://www.economist.com/research/styleGuide/index.cfm?page=...