On having another look Evaleigh should be Eveleigh, apparently lessees of a portion of Holcombe Barton.
The timeline I have for Thomas is:
c.1806: born Devonport or Ottery St Mary
1824: London - Enlisted 94th Foot
1829: Gibraltar - married Anne Peake
1830: Gibraltar - birth of son James Robert
1833: St Sidwells, Exeter - birth of son John Francis
1835: Falmouth - birth of son Thomas
1837: St Sidwells, Exeter - birth of dau. Emmeline
1839: Falmouth - birth of dau. Ellen
1841: Devonport - 1841 Census, Stage Coach Guard
1844: Falmouth - Death of wife Ann nee Peake/Pakenham
1845: Plymouth - marriage to Sarah Hambly nee Bond, widow
1851: Liskeard - 1851 census 'London Inn' - with second wife and daus. Emmeline and Ellen
1861: Liskeard - 1861 census 'London Inn' - with second wife and daus. Emmeline and Ellen
1863: Death by suicide - no death reg. uncovered but probate refers to Sarah Relict and Frederick Channon of Exeter, brother
The parentage I currently have for Thomas is James b.1786 Ottery St Mary and Ann nee Giles. This James was a long time member of the Devon Militia, finishing up as a QMS (which I equate to a civilian commercial clerk) which is I assume how he became a Chelsea Pensioner. During the Napoleonic years the Militia would have been based in or around Devonport where Thomas was born. Afterwards, James & Ann spent their entire lives in St Sidwells Parish, Exeter which is where Thomas went after leaving Gibraltar - coincidence?
A further wrinkle, the family notes mention an 'Old Uncle Harry' cousin to the writer's grandfather (James Robert). This would be Henry William Channon, b.1833 Bridgwater, Somerset to James Channon MRCVS & May Ann Blackmore. Henry William died in Boorowa NSW in 1921 and was buried at Frogmore. This would make his father James (Vet) a brother of Thomas (Gibraltar) but he doesn't appear on my list of children to James and Ann of Exeter.
Having said all that, these notes have to taken with a grain of salt eg. "Grandfather James Robert RN and his father Thomas fought at Crimea 1854 and at Balaclava under Duke of Wellington." At that time James Robert was at HMS Fisgard undergoing engineer training transferring to HMS Rifleman in Sept 1856. Thomas was in Cornwall, England.