Thank you everyone lots of useful information there. Therefore the consensus is that he was born 1899 and was a Van Man for a railway company. The 1939 register extract is from 10 Kingston Road, Cardiff
Current thinking is that the Douglas B Reeves with him is his illegitimate son David Bryant Reeves born 1930 Llanelly as David Bryant, son of Violet Elva Bryant (1910). David going on to marry a Valerie Isadora Williams.
I have been trying to find more about Ernest with no success. There is no Ernest “W” Reeves birth registered in Dec Qtr 1899 or Mar Qtr 1900. Ernest in 1939 state he was married and there is a marriage of an Ernest Walter Reeves to a Sarah Miriam Russ in 1918, in Cardiff, they had a son also called Ernest Walter 1918, who baptism address was 14 Station Road Cardiff, who died later the same year. Whether this is the same Ernest I don’t know. I can’t find the couple in 1921 or any obvious candidates for Ernest W Reeves in earlier censuses.