Thanks for the two FLAC rips, GradyTate, which replace lossy versions I had.
Re DWLP 3269 oddly I noticed the same flaw in the recording of track 23 (Kenneth Essex's Desperate Moment of Two Ronnies fame) on this FLAC copy as was on my lossy version. It comes as the third chord (G minor for you musicians out there!) is played at the very beginning. The same flaw doesn't appear on other releases of the track on DWCD 0102 and DWMIL 008 or on A8detective's DW 2551 78rpm rip. I don't know if it's a tape drop-out from the master or whether it's caused by compression artifacts. Though Lossless Audio Checker confirms that the FLAC version is genuine and not upscaled. So a bit of a puzzle.