A paper by Sally Sims and Peter Dent of Oxford Brookes University explores this subject, albeit in an urban environment.
They found that if an overhead line is within 100m of a property it reduces the value by up to 17% whereas if a pylon is within 250m of a property it can reduce in value by up to 21% compared with a similar property further away.
Just having a view of a pylon from the front of the house has a negative impact on house prices (-14.4%) although this is reduced to (-7.1%) for a rear view.
Ask yourself; what have I done to deserve this! How much value will my house and my neighbours houses lose collectively and why should I have to accept this? Just the thought of it makes me feel ill.
This is all part of the negative externalities that I blogged about in an earlier post.
Reference: Sims, S. and Dent, P. (2005) High voltage overhead power lines and property values: a residential study in the UK. Urban Studies. Vol.42(4), pp.665-694.