Hi Bazza
These are the only DELLER/DELLARS that I could find living at Lilley in 1851. Perhaps Thomas remarried?
Rick
1851 Census. HO107/1710 Folio 343a
Lilley, Hertfordshire.
DELLARThomas, Head, Mar, 56, Ag Lab, b Offley, Herts
Mary, Wife, 39, Straw Plaiter, b Bowridge End? Bedfordshire
David, Son, 10, Straw Plaiter, b Lilley, Herts
Fanny, Dau, 8, Straw Plaiter, b Lilley, Herts
Thomas, Son, 5, Scholar, b Lilley, Herts
Folio 347b(Visiting James & Harriet BROWN, both age 31, born Lilley & family)
DELLAR John, Visitor, Unm, 21, Ag Lab, b Lilley, Hertfordshire
Folio 348b
DELLARJames, Head, Mar, 33, Garden Labourer, b Lilley, Herts
Catherine, Wife, 30, Straw Plaiter, b Lea Green, Herts
Harriet Emma, Dau, 7, Scholar, b Lilley, Herts
William Asa, Son, 3, b Lilley, Herts
Folio 349a
DELLARCharles, Head, Mar, 37, Ag Lab, b Lea Green, Herts
Mary Ann, Wife, 44, Straw Plaiter, b Lilley, Herts
Dinah, Dau, 7, b Lilley, Herts
Sydney, Son, 6, b Lilley, Herts
James, Son, 3, b Lilley, Herts
Eliza, Dau, 1, b Lilley, Herts