Ally
I don't believe Simpson changed any corridors. He took out, added and moved bunkers.
Near as I can tell, Colt created 3 (maybe Simpson did the detail work), 4, 5, 6, 10, 11, 12, 13, 16 and 17 essentially from scratch. He also drastically changed the following holes, but used bits of he old course:
#1 uses Old Tom's still existing 1st & 2nd.
#2 is essentially the same and therefore an Old Tom hole.
#s 7 & 8 seem to be created after 1896, but before Colt.
#9 uses old 11th but changes tee to better use the wall - so this is a true combo of Old Tom, Wauchope and Colt.
#14 may use part of the old 13th - head in same direction
#15 may use part of old 15th - head in same direction.
#18 uses OTM routing.
If we add in the significant bunkering of Colt, easily 60% of Muirfield can be attributed to Colt. However, and importantly, I don't think we can say the general shape of the routing as we know it is down to Colt. I think this may be important because it culd well be that Muirfield's routing may have been one of the primary courses which started the idea allowing the wind to attack from all quarters and hence a break away from the traditional out n' back design when the land allowed.
Simon, it was a typo. If you could take the map above and compare notes while at Muirfield it may reveal some interesting info.
Ciao