Historical regional GDP series for the United Kingdom and for Great Britain for each of the census years between 1861 and 1961 are now largely complete though with no estimate for the wartime year, 1941. In the absence of data for this year, this note reports the data sources for and resulting estimates of regional GDP for the two years 1935 and 1938. Estimates are presented for both GB and the UK. They suggest that the worsening regional inequality observed between 1911 and 1931 continued to the mid-1930s with a reversal of this trend by 1938 that continued through to 1951. In addition we take the opportunity to consider two issues that arise from making long-term real terms estimates: first, what differences would emerge in the estimates had we used nominal data (where available); second what is the likely impact of base year on the long-term real estimates.