OK, as promissed here's my bodged "repair":
Here's the dent as it was:
Firstly things got complicated when I looked for the interior of the dent only to find that it was an area which had already been repaired... the small hole with a filler worm entering the inner wing gave it away...
Despite this I thought that I could still try pushing the dent out a bit to make it less noticeable. So investigating how to go about it I saw that by removing the headlights I would be able to push against the chassis uprights behing the grill. So out came an old car jack and a suitable length hammer:
By repositioning the hammer handle inside the dent and gently winding the jack I gradually pushed the metal to a shape closer to it's original.
The problem was knowing when to stop, having filler in the area already, and using such a crude method it was always going to be rough but in the end I left it like this. Far from perfect but at least the paint is intact:
I'm sure that with more patience and by spending more time I could have got it better, but considering that from a few meters away it's now much less noticeable than before I'm fairly happy to live with it as it is until respray time when the car reaches 25 years old next year.
These are sensations as hard to forget as they are to ignore.....