http://www.forum.forest-of-dean.net/index.php?mode=thread&id=7031

so we can be sure the marriage was post 1901

1901 9 St James Barton
Emily Clifford abt 1839 Calns, Wiltshire, England Head Bristol, Gloucestershire
Henry C Clifford abt 1875 Clahill W Calne, Wiltshire, England Son Bristol, Gloucestershire
William R Clifford abt 1881 Bristol, St James Son Bristol, Gloucestershire

and if this a child before 1914
Name: William M Clifford
Year of Registration: 1914
Quarter of Registration: Apr-May-Jun
Mother's Maiden Name: Briant
District: St Pancras (1902-1977)
County: Greater London, London
Volume: 1b
Page: 246