You could try the (remote) possibility there might be a local wireless ISP - best list I know of is on the ISP Review site (by area): I get 11Mbps/5Mbps down/up enough for everything, at over 5 miles from a transmitter, but speeds and costs can vary a lot between operators depending on age and type of infrastructure and their policies. Disadvantage is need for line of sight to their transmitter, install cost for an aerial and requires a cable router.
Just a thought, is the mast a radio or TV mast (though may also have a mobile phone install), I recall there is an (out of date) mast finder on the Ofcom site which shows the location and operators with service on specific masts, (which I think is updated now only for 3, voda and O2). Most specific phone masts are I think limited to 15m height or so? The ops have coverage checkers, though they have seem to have quite high margins of error. Three manage (from a dongle without any signal amplification) from my small rural mast at about 2 miles (through a housing estate) a speed of up to 2.5Mbps/0.3Mbps) and seems to be consistent.
Edited by smurf46 (Thu 31-Mar-11 12:15:07)