Cheers Al - just had a look and seems to have been stuck on by two blobs of black silicone - there are no visible bolts heads under the hood, unless they are under the heat reflective stuff.
I put a Porsche emblem sticker on the bonnet of the 914 rather than a badge.. if thievery is a worry, then perhaps a decent quality TVR logo sticker in the right size would fill the gap.
Perhaps you could get a nice new one, and fit it to the upper left corner of the grille (as seen on a piccie of the prototype Chim, its very effective).
You could also wire it to an invertor, with 5Kv across it when the alarm is on Wouldn't kill, but it would give a hell of a belt.
Hmm... reminds me of the days the Beastie Boys... scrotes whipping VW badges...
First one nicked.... replaced but with razorblades between grille slats (fingers thru' grille to prise out badge)..... badge still there, but with added crimson hue
Check the prices at your nearest dealer first. The same thing happened to me (badge nicked) and I paid less than £20 for a shiny new one at TMS...they rarely go for less than that on EBay.
porker badges secured with 2 mini bolts through hood, but a proximity alarm, seems to have paid off, as last badge, (although not screwdrivered off) damaged paintwork