"I have looked at a UK road atlas and not been able to find a Milford in Wiltshire (a land locked county)..." Milford, Wiltshire, is now a suburb of Salisbury, East of the City centre. It may be land-locked but it is on the site of a complex merge of rivers... leading to the sea. I would look for a baptism in one of the Salisbury churches. Best regards, John LOVE