Thank you for the suggestions. I have to admit that, so far, I have not found baptism records for John 1851 and Thommos 1856 but, if the record is for one of them, it would be a large gap. 15 - 20 years.

John did not marry Sarah Yemm until 1874 so it is unlikely to be a case of having to be baptised before getting married.

I can find no records for Thommos, other than the 1861 census where he is living with William & Tryphena.