@ Acorn: Spot on, that solves the flashing issue. Talk about missing the bleeding obvious re the links! Why isn't # correct?

@ Chris:
...horses for courses and all that.
Indeed. Using these additional layers is my prefered way of working.

I have a horrible feeling I've missed the mark and gone off on a tangent, but have fun with the file anyway.
Yes you are missing something but I'm off out & will explain later. Thanks for your input.

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