a campaign run by the ENCAMS (‘Environmental Campaigns’) charity to persuade people not to leave rubbish in public places. The phrase is widely used on signs, etc. put up around the country.
KEEP BRITAIN TIDY
Meaning of KEEP BRITAIN TIDY in English
Oxford guide to British and American culture English vocabulary. Руководство по британской и американской культуре, Оксфордский английский словарь. 2005