Westminster also won the media relations category for its lobbying of Wrigley UK to help tackle the problem of chewing gum on streets.
The PRWeek-sponsored Best Campaign Award went to Pendle Borough Council for a recycling drive.
Kirklees Council won the Best Publication/Leaflet Award for a mailout encouraging GCSE students to study for their exams. CIPR Scotland chairman and awards judge John Brown said the campaign 'was unique in getting young people to believe they can achieve'.
Warwickshire County Council was 'highly recommended' for its leaflet on council tax charges and the cost of local services.
Liverpool City Council won the internal comms category for its diversity forum and efforts to celebrate team achievements.
The PR on a Shoestring Award went to Telford & Wrekin Council; Cambridge City and Cambridgeshire County councils won 'Successful Partnerships'; and Hackney Council won 'Best Consultation Campaign'.