To get to our house we have to come down an unadopted lane(track!) This lane has 2 houses at the top of it either side that just about use it, another house further down on the right directly off it, another on the right that is accessed off it down a long drive and then our neighbours (1 bedroom house) on the right which is joined to ours (semi). All houses are 100 - 200 years old. On the left of the lane are open farmers fields. At the bottom of the road (our house)- dead end and a common. There is a small gate onto the common and we are led to believe that this is to allow access only to those that have commoners rights, although when we moved in 4 years ago it had not been used for a very long time(very overgrown until we cleared it). We also are led to believe that the lane is for access only to the houses.
We have no problems with people walking up and down accesing the common (rights or not) but we do object to our neighbour (1 mother and 4 children - yes in a 1 bedroomed house!) who seem to think it is a car parking lot. We all have decent sized gardens and we all have provisions to park off the lane. The 2 older boys obviously have friends with cars and their hobbies are doing up cars - again not a problem, but they insist on parking at the bottom of the lane i.e. outside the front of our house, right in front of the kitchen windows. They do not quite obstruct access, but it is soul destroying to find we travel the extra miles each day to what was our dream home to come home to what looks like a council estate and cars parked up outside our house. Common courtesy keeps everyone to their own areas but they just seem to spread everywhere. They have plenty of room to accommodate a drive at the back of the house like everyone else. I don't think we are being unreasonable and can't believe it upsets me so much. Is there anything we can do apart from park our cars there to stop them? (Defeats the object of the views. I have spoken to them in the past and they stave off for a while and then revert back.
Any help would be greatly appreciated.

I can't really help other than say your home sounds lovely! And I see why it upsets you.
I would park my own car/s outside. It affects the view but surely in time they will get the message that it's not on.
Or I'd hire a digger and park it outside theirs.

Or just take to parking yours sideways outside their's blocking off the final bit of the lane

Or make the land such that it can't be parked on.... sharp paving anyone? piles of grow bags?

Thanks for the thoughts. Yes it is lovely although it did resemble a cow shed when we first moved in, my husband has worked really hard at making it a beautiful home.
I hate confrontation and don't want to make ill feeling (although already there) I wonder where I'd stand planting a couple of trees i.e. flowering cherry, laburnum?

Why don't you speak to your neighbour first? She might just be completely unaware that she's bothering you.

If the land they're parking on is yours and you get no joy from your neighbour, then plant a few trees.

Won't planting trees defeat the issue? They will block your view.

In the short term I would park my own car/s there, and see how it goes.

Isn't it amazing how even in the middle of nowhere parking causes strife!

Have spoken to her on several occassions, just don't understand why they can't park them outside hers! Think the trees would look prettier than cars but the piece of land is unadopted and don't know where I would legally stand.

Well, I know it's tedious and probably makes you feel like a moaning minnie, but I think you have to keep reminding her. If you say "look, I really appreciate it when your lads park their cars round the back of your house - I know it's a nuisance for you to keep reminding them, but it makes a big difference for us to have the lovely views" then it doesn't sound like it's her fault, and it accepts that with 4 kids, she's probably run off her feet. Or you could have a chat with the older lads yourself - I remember that when I was that age, I would be inconsiderate without thinking what I was doing was Really Really annoying to other people.