A census of the population of the United Kingdom is taken every ten years. The 2011 census was held in all countries of the UK on 27 March 2011. It was the first UK census which could be completed online. The Office for National Statistics is responsible for the census in England and Wales, the General Register Office for Scotland is responsible in Scotland, and the Northern Ireland Statistics and Research Agency is responsible in Northern Ireland.

The 2011 census for England and Wales included around 25 million households. Forms were posted out to all households, using a national address register compiled by the Office for National Statistics with the help of local authorities. Lockheed Martin was awarded the contract to provide services for the census: printing, a contact centre and data capture and processing. The contract was for £150 million, about one third of the total £482 million cost. Some people called for a boycott of the census over the involvement of Lockheed Martin, but as the Census is used to distribute money to local services a council may lose £22,000 over 10 years for each person who does not complete it.

35,000 people were employed to help collect the forms.

There were 56 questions. Several were new. It asked immigrants their date of arrival and how long they intended to stay in the UK. There were tick boxes for same-sex civil partnerships. National identity included English and Welsh. Ethnicity included Gypsy or Irish Traveller and Arab. People were asked how well they could speak English. There was a question about the number of bedrooms a household has, as well as the names, gender and birth dates of any overnight guests.^[1]

The questions in Scotland and Northern Ireland were slightly different from those in England.