Markfd wroteI still can’t see any sign of a screw head, it looks more like some sort of press fit pin. It is a very early Milner. The diameter on the outside looks much bigger than the other two.
Most unusual. Looks like it’s a rivet in the middle. If so you could either drill it right through or just cut away the countersink on the outside and punch it in with the screws firmly in place to take the strain.
Once the hinge is free the door will lift straight up and out.
Might be that a rivet was used if the original screw thread was damaged. No matter, hope you get it out OK.
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