JP5 Inst panels – What colour grey?

Using the vast font of knowledge amongst the forumites, can anybody tell what the BS spec is for the grey used on Jet Provost 5 panels (and indeed interior)
I’ve looked through the AP’s I have and done some ‘googling’ but seem unable to find it.
The collection of panels I have are from a variety of sources are all different shades so some guidance would be welcomed.

Offers?

Thanks