I echo what the others have said -- the only folks that I know of who probably make any money are the ones who write books, like a collection of ghost stories, etc... Even then, the audience is pretty limited and I doubt the writers are rolling in dough, especially after publishing costs and all the other little extras. I don't think many paranormal investigators have quit their day jobs.
However, depending on how "touristy" the area you live in is, and I would assume Yorkshire would get a good number of tourists, you might want to consider doing a ghost tour of local haunted sites. I would think that would be a good location. I know London has several. I had wanted to take one when my husband and I were there but never got the chance.
You would need to do a lot of research on local haunts, interview people, get their permission, and of course, advertise your tour. I've been on walking tours of San Antonio and several in New Orleans and I know a lot of large and even medium sized cities have this sort of tour now.
The tour guides charge about $10 per person and the tours usually last about an hour. Normally, they have about 10 or more people on each tour. Not bad at all for a night's work. If it were something you did frequently, and most of these guides do, it would be a great way to stay in shape, doing that much walking every night! I would suggest going somewhere where they have one and seeing how it is done.