1921 Census of England and Wales, General Report with Appendices, Table 23 : " Distribution of 1,000 Private Families by size of family, 1921".

  Proportion per 1,000 Private Families consisting of the
following numbers of persons.
1921.
Average No.
of persons
per family.
1. 2. 3. 4. 5. 6. 7. 8. 9. 10
or
more.
1921. 1911.
England and Wales 60 177 208 186 139 94 60 36 21 19 4.14 4.36
London 116 207 204 164 116 77 50 31 18 17 3.79 4.15
County Boroughs 50 170 209 191 144 97 62 37 21 19 4.21 4.42
Other Urban Areas 50 171 212 192 143 96 60 36 21 19 4.19 4.40
All Rural Areas 60 180 205 182 138 95 61 37 21 21 4.16 4.31