Thanks for the replies. The job's done, unfortunately I didn't get pics. In the end I went in through the grill, like Abyss. The steps were unscrew the 5 bolts holding the grill in place, remove the grill, remove the black plastic lining behind the grill, use a socket to unscrew the bolt holding the badge on from underneath (7mm I think?), then use floss to cut through the sticky holding the badge to the bumper. It's a simple, if fiddly, job and probably took 1 hour all in.
It's also a good opportunity to clean up/ detail around the grill and the grill itself. I also took the grill to pieces, removed the trident and re-sprayed the mesh matt black, it suits the dark paintwork and shadow coloured wheels on my car much better than chrome.
Cheers
John