Hello David,
Do you know that George and William are brothers? I can find George on the IGI, but although I think I have found William on Free BMD (Dec 1842 East Grinstead 7 305), I can't find him on the IGI. This could mean that he was baptised at Lingfield, rather than East Grinstead.
If the Elizabeth that Sharon found is George's mother, then in 1851 she is probably the one in East Grintead Workhouse, still unmarried and with Charles E Chapman, 8 months. (HO107-1641, Folio 232, page 51).
Her baptism, from the East Grinstead PRs: 23rd Nov 1823, d/o Henry and Mary Chapman, abode East Grinstead, father's occ. Labourer.
From the SMI, her parents possible marriage:
Heathfield, 15 Jan 1810
Henry Chapman (East Grinstead)
Mary Bottooth (this could be a mis-transcription of Bott Tooth, I suppose)
By Banns
The 90th Infantry is the 90th Light Infantry (Perthshire Volunteers). They appear to have been posted abroad 1835-46, but no doubt retained some presence at home.
The best contender I can find for William Simpson in 1841, is a Railway labourer, age 25, living in a hut in Crowhurst Lane, Godstone. This is not far away and East Grinstead would be the nearest town. Godstone station opened in 1842, so probably moved on. Simpson is not a local name.
HO 107/1077/9. Enumeration Distict 13. Folio 7. Page 8.
Regards,
Phil