Visited West Glam Archives today. Checked baptism register for St Peter (Cockett) from 4 Jan 1919 to Oct 1926 - no entry for a Basil Belcher. Also checked -
St Paul (Sketty) - up to Aug 1925
St Mary (Swansea) - up to Apr 1923.
Again, no entry for a Basil Belcher.
regards