It appears from what I have read the odd individual has made some weird navigational errors in previous years.
First time I rode the BCM I spent half an hour looking for this control. How I laughed when I eventually found it.
See also the control at Bulch on the Brevet Cymru. Both examples of Controls off/set back from the main route.
I don't think it applies so much nowadays as it's more recognised there are more new riders taking part, but go back a while and the attitude was very much that there was no need to signpost controls because, 'everybody knew where they were' and providing any route guidence beyond a basic routesheet was to be abhored as 'spoonfeeding'.
That always struck me as a pretty callous attitude. It may work fine for stronger riders and those riding in groups but things are rather different at the back of the field where tired tailenders riding on their own are working hard simply to get round, and turn-offs for controls which aren't actually where the route sheets suggests they are are easily missed. See also routes that involve obscure off-road tracks and cut throughs which play havoc with follow route GPS routes.
Gosh, did I say that out loud?