It is worth mentioning that I ended up drilling and tapping the rear wheel frame for the front stays of the rack (the parts that need cutting). IIRC I used 4mm screws. I had to sell my M21, a brilliant bike, as it was too large folded to fit the locker on my boat. I am still looking for a replacement, that folds to a smaller size but with the same capability in a variety of riding conditions. Haven't managed that yet.
All the best, Ian