The Westcott NDB gets paticularly busy as many of the aircraft from the large schools at nearby Oxford and Cranfield use it for IFR training at lowish (i.e non airways) levels in addition to VFR general handling. I've used it many times during my training and my instructor always referred to it as Tin Alley and was paranoid about lookout in that area. Add in all the regular GA stuff and it gets very crowded in a small area of uncontrolled airspace.
Other NDBs/VORs (away from controlled airspace) can be a lot quieter, but unless you have good local knowledge you won't know until you're in the thick of the action.