I now have the marriage certificate for William Snow and Frances Bellenger in August 1843, which took place in Hutton, Essex, and was originally found by jonw65. One of the witnesses is Lucy Bearman, the married name identified earlier on this forum of Lucy Ballenger. This seems to confirm that jonw65 was correct in suggesting that Frances Bellenger followed her sister Lucy to Essex.
Many thanks to all involved in this, it fills some big gaps in the lives of the children of my 3x Great Grandparents. Some of the searches made on my behalf were truly revealing. Without your help I would not have made these connections.
Once again, many thanks.
