Works made by civil servants come under Crown Copyright, according to
the Copyright, Designs and Patents Act 1988: see an explanation and link
to the legislation on The National Archives[1].

The copyright year is supposed to be the date the work was created,
which in this case dates back to the original commit in 2011:
8fa27720.

[1]: http://www.nationalarchives.gov.uk/information-management/re-using-public-sector-information/copyright/crown-copyright/