An update - a good breakthrough. I tried again with a professional genealogist to knock down a brick wall. I could not find my paternal GGGfather except in the 1881 census - no birth record, no marriage record. This would be a good lesson for beginners.
In the 1881 census [taken at English Bicknor, Gloucestershire] his place of birth is shown as Colwell, Herefordshire. There is no Colwell in that county but there is a Colwall. For that village there is an amazing web site with baptisms going back for over 300 years. No Thomas Southern.
One of his sons is shown as born at Chepstow so that was another possibility but drew a blank for Thomas. I obtained his death certificate which indicated 1840 or 1841 as his year of birth whilst the census indicated 1845 or 1846.
I investigated the town of English Bicknor and found it adjoined an area known as Coldwell or Coldwell Rocks. This almost lead me to the correct conclusion but still no trace.
I wrote to Eleanor Harris, a Herefordshire researcher. She came up with 1841 and 1851 census data for an area within Huntsham in Goodrich parish. This showed a John and Mary Southan with a son Thomas born 1840.
I investigated this further and found that the Coldwell part of Huntsham nd the Coldwell of English Bicknor are one and the same place! Huntsham and English Bicknor are in two different counties but are only one and half miles apart. Close study of gazetteer entries nad an ordnance survey map show no houses on the Gloucestershire side but a few cottages on the Herefordshire side.
So, welcome back Thomas Southern, not hidden in the witness protection programme but hiding under a slightly different surname.
