Well, we used several of the ideas and finally managed to fix the light. I took a photo of it with my phone, which let us see what we were up against. The initial attack with needle nosed pliers had given us a bit of space to work. Then a large stubby screwdriver rammed into the remains of the bulb started the bulb base moving, and then it was possible to screw it out without too much trouble. New bulb in and working just fine. Thanks for all the ideas.