Re: 1978 MGB Headlight Ring
Some people use a paint-can opener. It is a metal rod, bent into a circle on one end and it has a kind of hook on the other.
Reach under the ring and grab the back lower edge of the ring with the hook and pull sharply. The ring should pop off.
I made a better hook from a small screw driver by heating the end red hot, pounding it flat then turning the end over with a pair of locking pliers. This allowed for more hooking capability.
Guinn