Hi Sigplat,
Here's the same family in 1851, except William is married to Elizabeth rather than Sarah, but the children all match up
ref HO107 1614 folio 286: 2, Camden Lane, Tunbridge Wells
William Martin head mar age 33 builders labourer born Tonbridge
Elizabeth do wife mar age 32 born do
Sarah do dau age 11 scholar born do
William do son age 9 scholar born Tunbridge Wells
Edward do son age 6 scholar born do
Mary do dau age 4 born do
Henry do son age 2 born do
xx Carol.