The plan:
Bore out the broken end of the hook, that was originally just screwed into the wood, having a wood screw form on the end which had sheered off. Then make an adaptor to slide in upwards, drilled and tapped to accept the end of the original hook, that had had a male thread cut on it.
Conveniently the hook was bent from 1/8" material, So the wood was bored out 1/4" (fixturing was fun !) and the 1/8" Whitworth threading gear located, an adaptor turned up out of a scrap of steel and all glued together with loctite high strength retainer