As per your other post about William, brother of James Clifford. --- James ended up in Wales.
He was a Postal Clerk and Telegraphist and lived in Neath in 1939.
He married Annie E. M. Thomas in 1934 in Newcastle in Emlyn Registration District.
You will be able to find children born to this marriage by going to the General Register Office Website. If you haven't done so, you will need to register - but it's a free site.
You can search the Birth indexes looking for surnames of Dickinson with a mother's maiden name of Thomas after this marriage. You will have to do it by searching for males and females separately and can only do it with a plus or minus 2 years of a date -- hence start with 1936 and plus or minus 2 years and so on.
You can also search on Free BMD with the surname and mother's maiden name at this period -- and do it for a longer range of years without the necessity of the male and female separation. You need to look at any coming up in Welsh Registration Districts,
The birth date of James was 19 July 1906 -- so you can search for his death in Wales on Freebmd.
If you are not clear about any of this just reply to this message and seek clarification -- but you should be able to find his children and him.