Upon further investigation…

…more of the same.
WHY?
Why not?   
I've been even more sedentary than usual today - BUT - I investigated The Beast.  It may well be an incorrect ID. I'm open to suggestions - another BUT - the page I first visited had "British caterpillars: how to identify 10 common species."
Of the ten, the "Speckled wood butterfly (Pararge aegeria)" looked the likeliest; on the strength of which - Instigate PLAN B = keep it safe and keep an eye on it. 

I feel I have to award him/her 11/10 & ***** for skill and stealth.  
Its M. O. appears to be - Scoff 2/3 of the petals, lurk longitudinally along the last one THEN set about the seed capsule, see thumbnail of it's probably its last meal.

NOT 100% accurate info - the "Macro" was Canon EOS 600D  I'll see if I can find EXIF & return. It spake thusly:-
"Canon EF-S 18-55mm ƒ3.5-5.6 IS II"