I did a free search on the 1921 census with Arthur Roberts born 1901 occ carman only one result
Arthur Roberts 1901 born Langford, Bedfordshire, England Parish Langford Registration District Biggleswade, including Arthur, there is an Ephraim & Rose and 5 other persons listed
This is the 1901 census
Arthur Roberts
Age: 3 Weeks
Relation to Head: Son
Father: Ephraim Roberts age 21, bricklayers labourer
Mother: Rose Roberts age 21
Birth Place: Langford, Bedfordshire
Registration district: Biggleswade
Piece: 1498
Folio: 120
Page number: 7
I think you can cross off this Arthur Roberts from your list as I think he marries a Gladys died in Biggleswade 1982