There is no equivalent BS 970:1955 EN Grade for BS 970: 1970 015A03. The nearest equivalent is BS970 Pt1 1996 040A04 being equaivalent to the old EN grade 2A or 2A/1 but the specified C and Mn levels are slightly higher. Depends whether this is it is important or not. You coud try asking a stockholder to supply the 040A04 to the compositional limits of the old 015A03, but the Mn will bver be low enough to meet that low of 0.30% max.
For info:
015A03 was 0.06%C max, 0.30% Mn max.
040A04 is 0.08% C max, 0.30 - 0.50% Mn max
En2A/1 was 0.1%C max, 0.50% Mn max
En2A was 0.12% C max, 0.50% Mn max
ENB 10083-1:1991 is for quenched and tempered steels. CR22E has a specified C of 0.17/0.24% and Mn of 0.40/0.70% (plus maximum Cr+Mn+Ni of 0.63% Max) so it's not really the same.
Hope this helps
Andy