Maybe a long shot for your wild card? There is a William SIM who is an architect mentioned in the papers selling/renting some property in Windsor in 1863,
The Times (London, England), March 14, 1863, Issue 24506, p.6
Also bankrupt in 1866:
"SIM, William (June 23), architect and surveyor,
Danes Inn Strand, and New Windsor, Comp. (14,422) of 5s immediately"
Perry's Bankrupt Gazette, Saturday, July 21, 1866, Vol. XXXIX, Issue 1998, p.607 / 608
and bankrupt in 1878
The Standard, Tuesday, March 5, 1878, Issue 16728, p.6
I think this is him in the 1871 census at Windsor:
William Sim 55 Scotland
Eliza Sim 52 Dorchester
Huson W Sim 29 Bloomsbury, Middlesex
Wm C Sim 25 Middlesex
Frances M Sim 18 Chelsea, Middlesex
Scott B Sim 17 St Mary Abbot Kennsington, Middlesex
Vincent C Sim 15 St Mary Abbot Kennsington, Middlesex
Hubert Sim 13 St Mary Abbot Kennsington, Middlesex
Osburne Sim 10 New Windsor, Berkshire
Sarah Simpson Servant 27 Buckenham, Buckinghamshire
Emma Pearce Servant 19 Eton, Buckinghamshire
GBC/1871/1300/0179