You say Thomas was born in Dawlish Devon? Mother Marion, Father Thomas, brother Thomas who all lived in "Westrom" at, I presume, the time of Frederick's conviction.
I find the following IGI extracts ,and the Census interesting - and wonder if the Dawlish part, relates to his mother not him - or else he might have been born Dawlish Devon, but christened Westerham Kent.....
IGI Parents: Thomas WOOD and Maria
IGI Issue - all christened in Westerham Kent:
Maria WOOD - 28 Jul 1816
Frederic WOOD - 13 Dec 1818
Thomas WOOD - 29 Apr 1821
Elizabeth Jane WOOD - 25 Jan 1824
John WOOD - 28 May 1826
Harriet WOOD - 10 Aug 1828
Robert Jewell WOOD - 22 May 1831
Eliza WOOD - 28 Sep 1834
FreeBMD:
Robert Jewell WOOD died in 1837, registered SevenOaks Kent (Which covers Westerham)
It may be that the other son of the family, John died before 1841 too? Leaving only Frederick and Thomas as the two surviving brothers? So explaining why you have reference to your Frederick with brother Thomas only?
1841: Westerham Town, SevenOaks, Kent
HO107 / Piece 485 / Book: 14 / Folio: 29 / Page: 21
Thomas WOOD 45, Bricklayer J(ourneyman)
Thomas WOOD 20, Bricklayer J(ourneyman)
Maria WOOD 45, Not born in Kent
Harriot WOOD 12
Eliza WOOD 6
ALL born in Kent (except Maria)
1851: "The Chequers Inn" - Village of Southborough, Parish of Bromley, Kent
HO107 / Piece: 1606 / Folio: 113 / Page: 20
Head: Thomas WOOD 57, Licensed Victualler, b Westerham Kent
Wife: Maria WOOD 58, b Devonshire
Dau: Eliza WOOD 16, unm, At Home, b Westerham Kent
Lodger: Edward OBEY 48, unm, AG Lab, b Bromley Kent
1861: "The Chequers" - Parish of Bromley. Kent
RG9 / Piece: 463 / Folio: 123 / Page: 10
Head: Maria WOOD 63, widow, b Dawlish Devon
Grandson: Thomas WOOD 7, Scholar, b Norwood Surrey
Servant: Elizabeth Mary TIPPEN 15, unm, House Servant, b Cudham, Kent
Cheers
AMBLY