« Reply #5 on: Friday 19 June 15 15:54 BST (UK) »
I'm afraid that alighting on Thomas as William's father seems to be to be jumping the gun at this stage, unless there's solid evidence. Definitely never ever rely on someone else's tree unless you've independently satisfied yourself that they've got it right.
Much better to trace William and see if you can find a birthdate/birthplace for him.
Have you found the family in any of the censuses? I see that William & Sarah baptised several children (below) at St Giles Cripplegate in the 1820s and 1830s. William's occupation was consistently Warehouseman - in keeping with "Manager of a warehouse" as he was described on WHH's 1865 marriage.
05 Oct 1823: Elizabeth Ann (born 21 Aug 1833; abode White St)
10 Jul 1825: Maria (born 05 May 1825; abode White St
10 Jun 1827: William Holman (born 02 Apr 1827; abode Love Lane)
03 Feb 1832: Edward Henry (born 28 Dec 1831; abode Cumberland St)
02 Mar 1834: Ann (born 31 Dec 1833; abode Hackney Rd)
19 Feb 1837: Emily (born 13 Nov 1836; abode Aldermanbury)
Ayr: Barnes, Wylie
Caithness: MacGregor
Essex: Eldred (Pebmarsh)
Gloucs: Timbrell (Winchcomb)
Hants: Stares (Wickham)
Lincs: Maw, Jackson (Epworth, Belton)
London: Pierce
Suffolk: Markham (Framlingham)
Surrey: Gosling (Richmond)
Wilts: Matthews, Tarrant (Calne, Preshute)
Worcs: Milward (Redditch)
Yorks: Beaumont, Crook, Moore, Styring (Huddersfield); Middleton (Church Fenton); Exley, Gelder (High Hoyland); Barnes, Birchinall (Sheffield); Kenyon, Wood (Cumberworth/Denby Dale)