The thing is that this particular organ that Trevor is getting ready to play for a wedding soon in a church where organ's pedalboard (which is unusually short) is not lined up with the manuals in the traditional way. This means that when he plays what supposed to be a tenor C he finds himself playing an A (a minor third below).
Trevor compares this feeling with mixing the pedals while driving a car. He rightly points out that "it's rather like finding you have your feet on the clutch and brake instead of brake and accelerator. It's very disconcerting and makes me feel rather incompetent."
Perhaps your organ also has the keyboards moved a little bit to the left? What to do in this situation?
How about centering yourself around the pedalboard instead of the keyboard?
In other words, disregard the manuals and sit where the C is in the pedals.
Of course, then you would have to adjust to the manuals but I guess this is easier simply because usually the fingers have a better contact with the keyboards and you could look down to see exactly what you play. It's not an ideal situation but at least a temporary solution.
Either way, if it's just one time playing, maybe you can get through it. But of course over time it would not be a nice experience for your body. With time, though, your body will adjust much more but the side effect of this is that you will have a more difficult time adjusting to the normal centered pedalboard.
By the way, the same can be said about the pedalboards which have very narrow or very wide keys (or organs with different stop layouts). These differences in organ design are something that we all must face when playing historical, unfamiliar and strange organs.
Another advice would be this - get acquainted with as many different organs as possible. The more diversified your experience is, the faster you will adjust. Part of the beauty of the organ world is of course that most of them are very different and unique.
Do you have any experience with playing not centered pedalboards? If so, please share your ideas of how you adapted in the comments below because they might be helpful to others as well.