Auxiliary Belt

[scooper1000]

I have just tried to adjust my Auxiliary Belt according to (haynes manual) it should be a relatively easy task, However I am assuming the last owner or garage has managed to turn the tensioner pulley by 180 degrees as the 16MM nut head you use to take pressure of the belt is on the opposite side than normal consequently I had to drop engine by a few inches just to get spanner on it.there was no way i could get a socket onto with ratchet handle attached...not wanting to drop engine further I am now wondering is my engine a 1 off or can these be put on wrong and something I can attend to in the future..
thanks