OK, further information
The transit and transit connect up to about 06 appear to have been made with a badge that looks exactly like the ST badge, but the replacement part is the same for both vehicles - the one shown above.
However
I've got hold of the replacement badge for the back of the latest Galaxy and it's the same shape and depth as the original ST badge, though the blue is slightly lighter and the letters and rings are very slightly raised - as if the original badge had an extra layer of varnish over the whole thing. That said, it looks exactly the same shape, depth, texture and colour as the front badge on the Zetec S in the showroom. (which uses the same badge/grille as the ST)

This badge has no pegs at the back at all since it's supposed to stick on the tailgate glass. I'm not sure if the S-max badge is the same, though I think it is even though the S-max badge is on the metal of the tailgate.
Part no 1437169, priced at a very reasonable £9.45.
I've not yet fitted it - for a start I've got to prise the transit badge off the grill - so if I can make the 2hr drive to FITP I'll bring it along to view.