Thanks Mark
Yes, I am inclined to agree with you but... yesterday, an M class merging with an X class flare, Start 1055, ending approx 1200 and almost the same thing happened again. The correlation on the start time is almost exact, the interference burst type changed at the dip of the X type..
Something strange going on.. Clearly a interference burst accentuated by a depressed or enhanced D layer?

BTW, I do get some interference bursts that I cannot correlate with a flare.. It's just these timings above that seem strange.
Here is one that didn't...

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Martyn