Sunday 21 March is Census day in England and Wales and continues the 10 year trend (except for 1941 during the Second World War) that started in 1801 with the first census. Here you can find population pyramids for England and Wales from 1911 to 2011 (except 1941) and information about these years as well as how to read the population pyramids.
The following files are available
You may want to organise your own census: you will need to think about the questions you want to ask and how people will answer them (validity and reliability) as well as how you might record the results.
More on population pyramids at