I have just looked this up
-1851 population census, taken on the 30th/31st March, was the first census to ask detailed questions re structure of the household, ages etc. Along with this census two other censuses were taken:- an educational census of all schools (including Sunday Schools) asking about the number of students, teachers and running costs, and a census of Accommodation and Attendance at Worship generally referred to as the Religious Census taken on the 30th March