You can find out who owns a property for £3 from
Land Register Online.
It's slightly more complicated for land (as opposed to buildings) as you can't do it directly on line. You need to send a plan of the area in question to your
local Land Registry office and ask them to do a search of the Index Map. They will then send you a list of any titles which you can then look up online for £3 each.
There's no chage for the Index Map search (providing the area contains no more than 10 titles). They prefer you to submit a 1:10000 OS site plan with your request, but these are not cheap. I've used an enlarged regular OS map with an aerial photo as backup, and didn't get any complaints.
John