I hate my chat with the estates person at our southwest power yesterday. He said that these dodgy companies offering big payouts are essentially pursuing a line about detrimental effects to house prices. So, if like us, you have poles in hedgerows away from the house, then the payout is small. We have 5 or 6 poles on our land, some are 3 wire high voltage, some single wire... loads of stays... 15 year lease would be about 800 quid. Apparently the 15 yeah lease is actually only 10 or 11 annual payments lumped together, and a 25 year lease is only 14 annual payments.
The estates chap also advised us that we loose any right re-siting, or redirection of lines/poles for the duration of the lease.