To let more light in, it could be carefully thinned and "windowed". If it is interfering with the lines for your neighborhood, though--as opposed to your house line--it will, sadly, likely need to be removed. It is probably worth checking with your local council, though, since I'm sure that your laws will vary somewhat from ours.

The tree would probably survive the removal of the branch that's catching the power line, but removing a lot of branches would as you say make it much less attractive and drastic pruning could indeed kill it. If you are keen to keep the tree it would be well worth calling in a good qualified tree surgeon to advise you and carry out any suggested work.

Thank you stern gram, Power lines are just visible going right through the centre of the tree canopy in the photos just posted, So there is no one branch solution, sadly.
Tugbrethil - we have lightly pruned it all over every year after it has finished flowering but it has come of the age where when we prune it it seems to grow like mad in reply and double everything we took off. These pics taken six years ago, tree much much bigger now. Main huge trunks/branches are very spread out the trunk split into about six branches about three foot off the ground, many years ago, and has grown upwards and outwards from there. The only solution is to cut it right back to those main six trunks/branches but this is my fear that those branches will be too old to shoot out again and the tree will die.

Looks as though you've had it then. What a shame. Its an object lesson in calculating planting distance from house in relation to eventual size of tree...

I'd keep the tree and live in darkness.

I am thinking of making the tree more transparent, rather than smaller. The latter would likely kill the tree, or at least ruin its shape, and make it more susceptible to wind damage. Windowing involves carefully thinning out selected large branches to allow spaces in the crown where wind and sunlight can come through. Depending on your local laws, the power line might just go through an extra large window of its own. Windowing is best done by a skilled arborist.

I really really hope this can be done successfully - best of luck with it.

Loking for something else re my magnolia I came across some info that says if you cut back hard it encourages the development of long straggly upright shoots and some dieback. What did you decide in the end?

Sorry to take so long to respond. Thanks to all who replied and still to date Steragram, I am undecided and have not yet braved the storm as it were. Still sitting in dark Lol
Will probably call in a local arbor Urborculturist? As the tree is too beautiful to risk losing. Will probably have to move the house! Ha ha. Anyway thank you everyone!

Lol Nicola...