It has been a while since I did take this shot and I did the flared border on it. It resurfaced as a ‘flared borders” when I searched my tags. Unfortunately this is all I remember about the PS2 process that I used to get the border. (Yeah, take notes Delio!!) Various attempts with the marquees/select/inverse and edit/fill option functions did give me various similar borders but without the flared burning into the black from the high light background colours. Can some one help in figuring out what on earth I did? It’s nice; I would like to use it again, thanks. :) :)

Have you tried "motion blur" or "radial blur"?
Otherwise select well inside the border of the picture, as thick as the border itself. Invert selection to have just the frame.
"gaussian blur" or any of the previous...

EDIT. Just reread what I wrote, I skipped a "feather" step before inverting the selection. Wooops

Ha! Thank you Pierre.
No I did not use the blur functions; however while trying your idea I realized that I had the marquee feather setting at 1 px. So that the inside black border line remained sharp. Once I increase it to 10-15px it fuzzed up and merged with the inside colours highlights nicely.
So for the communal record this is what I did, (certain that there is a much faster way to do it too, but !!!)
On a single colour image, with the feather setting set, for the example at an exaggerated 15 px  set a square marquee to form the inside line of the border.
Select menu, Inverse. You are now working only on the border area of the image.
Edit menu, Fill .
Contents window / use / colour select colour from the colour picker. I used blk. since it was my background colour.
Blending window / mode / color  burn (I know we spell it right). Opacity 100%. OK
Select menu, Deselect. Do the same on the other two images.
Assemble the three boarded images in a triptych as you normally do. :)

Neat trick, and wonderful triptych!  

Looks like the race on again  :)

Oh! I hope not, not another one! :-)

Oh yes it looks like it's on again... :D