The Transparency Agenda of the 2010/1 UK Coalition government promises to revolutionise government, public services and public engagement, by ‘holding politicians and public bodies to account, reducing the deficit and delivering better value for money in public spending, and realising significant economic benefits by enabling businesses and non-profit organisations to build innovative applications and websites using public data’, to quote the then Prime Minister. This is an ambitious programme with laudable aims, yet it naturally has limits.