The only William Coombs I can find on my Microfiche of Parish Record Christenings in Frensham (Surrey) is:
William Coombs christened 24 December 1820 son of James and Elizabeth Coombs. James was stated to be a papermaker.
The previous entry for a William was in the 1760's and he appears to have died when he was 2.
Siblings are (Christening date):
Mary Ann 11 April 1819
Peter 13 April 1823
Edward 18 December 1825 (shown as Coomber)
Other Coombs which appear in the 19th Century are
Henry 1829 (burial)
Susannah 1833 (burial)
James 1837 (burial)
Eliza 1840 (christened parents Stephen and Mary Ann)
I'm afraid I don't have any other Surrey/Hampshire microfiche, but I hope this is of help,
Steve