My 'hanger' is part of the lug.
Yes the 'thin metal strip' is there which allows small adjustment to the axle position (both sides), secured by the hex-headed screw.
Think we need a 'close up' of the RD (make/model) and rear RHS drop-out.
I wonder if your seatpost clamp (mechanism) screw (with its unaesthetic head protruding) is actually a replacement. Mine is a 'normal' recessed allen key job.
Another fruitful session tonight
Rear hanger WAS secured by a bolt that was way too long and was rubbing on the edge of smallest gear so found a much better nut and bolt and not convinced it's been chopped off.
Re measured rear drop out
Seat post is 25mm and top half fluted tried my selection of seat pin Allen key bolts but none were correct so retained original, managed to remove the bolt for seat clamp with an Allen key headed bolt.
Tried some 35 mm marathons in the rear and they would be ok if I decide to go that route.
55 stamped on what would normally be a brake bridge
All followed by a leisurely 1.5 miles and it rode 5.