Hello again all

Based at R.A.F. Morpeth, 4 A.G.S. had two Miles Masters on their books. Alan Lake's 'Flying Units of the R.A.F.' has DK957/B, and Air Britain's 'R.A.F. Flying Training & Support Units' by Ray Sturtivant et al has DK959/A.

DK959, however, doesn't appear to be a valid R.A.F. serial number. Does anyone have the relevant Air Britain R.A.F. Register book and can see if it's possibly 949 or 969? And what does it have for DK957?

Many thanks