1841 census
Mingoose vain, St Agnes HO107/149/3 folio 13 pg 19
John Delbridge 20 tin miner
Frances 20
Mary 3 months
all born in county
CaroleW has given you the 1851 when the family was in Crowan
1861 Hallenkein, Phillack RG9/1586 folio 33 pg 27
John Delbridge head mar 43 copper miner b. St Agnes
Frances wife 41 b. St Agnes
John son 19 copper miner b. St Agnes
Thomas son 15 Blacksmith b. St Agnes
Isaac son 13 copper miner b. Crowan
William son 11 b. Crowan
James son 9 b. Crowan
Jabez son 6 b. Phillack
Matilda dau 3 b. Phillack
Elizabeth Nicholas mother-in-law widow 67 b. St Agnes
marriage ref
John Delbridge sep qtr Truro vol 9 pg 319 with Frances Nicholas on the same page
Frances was buried 25-2-1869 in Phillack, abode given as Bodriggy, age as 49.
John also buried in Phillack 8-3-1882, aged 64, abode Guildford.
Possible baptism for Francis Nicholas, 28-3-1821 in St Agnes, transcribed as son of Isaac, miner, and Elizabeth Nicholas, abode Mount Hawke. They had already had a daughter named Frances who died aged 2 in 1818. The register shows 'dr of'
https://familysearch.org/pal:/MM9.3.1/TH-266-11610-165623-33?cc=1769414&wc=MMVH-VH8:n733885015You can use the opc database to search for Isaac Nicholas in St Agnes
http://www.cornwall-opc-database.org/If you use Nic for the surname, it will find variants. Marriage to Elizabeth Mollard, his burial and possbile baptism are there as is Elizabeth's baptism in 1793.
