I gave them a good dose of penetrating oil and hung the bumper up for a few months while I though about it...
Simple solution: take 1.7m of 25mm square ERW, cut ends to 25 degrees and securely tack weld to remains of both brackets. Hold the tube in a vice. Undo bolts. Fiddle the tube out of the bumper. 4/4 success


PS watch out for burning paint on the brackets
