The Lotus Grand Tourers

phantasm,
if those bolts are that bad it must be a long time since the bonnet was off, cam belt must be a priority

Update: I was able to remove the good bolt on the cracked bonnet side, felt like the whole assembly was made of nylock it was so tight! Upon removal it's removal I determined a bobbin rivet was in fact broken on the bonnet side. I repaired that. I replaced the bonnet bolt with a typical hex headed bolt I found in my parts box, that slid right in and was much easier to work with than the original bolt. I used a ratchet wrench (Spanner as you call it I think?) to drive the hex-head bolt in in seconds. Too bad I didn't have a matching set!

I then attacked the broken bolt, I started by backing off the lock nut completely, again with the spanner and got lucky in that it siezed on the rusty threads near the broken rusty tip and actually started to back the screw out!! So I was able to remove that broken bolt within a manner of seconds!! Whew!

I examined the good bolt and determined it had some metal and other dirt pressed in the threads hence the nylock nut experience removing it, I was able to clean that junk out and proceeded to replace the broken bolt with the good one for now. My intent is to get another hex head bolt once the stores open and replace the OEM part since the regular bolt head is so much easier to work with long-term.

So now I can now tackle replacing the coolant knowing I can get the bonnet off in good order. I'll save that for tomorrow.
Thanks again for all the input and things to watch for; Rivets in particular today.