Thomas may have remarried;
1861 Census
10 Sutherland Terrace,
Lambeth St John, Surrey
RG9/364/139/11
Thomas HALL, 63, Head, Mar, Managing Chancery Clerk to Solicitor, born Trowbridge, Wilthshire
(image looks like 68 to me ie c 1793)
Lydia W Hall, 51, Wife, Mar, born Beckington, Somerset
+ 1 Servant
Marriage FreeBMD;
Thomas HALL, Sept 1856, Newington, 1d 335
On the same page is a Lydia Wickenden WEST
Death Reg;
Lydia Wickenden HALL, Sept 1868, Lambeth, 1d 301, age 59
He may have also remarried to a Rachel BARKER, March 1871, Lambeth, 1d 497