When we brought our house we brought it because of its corner plot and large garden.
We get on well with our neighbours, they kindly asked if they could have a party at the end of our garden as they do not have the space in theirs.
We allowed them to use our garden because we wanted to keep the relationship good.
Yesterday I saw her put up a washing line in our garden! 
Neighbour must have thought that we were out, because dh took the teens on a day trip and must of thought I was out with them.
I am not happy that our land is being used and treated as an extension of their garden. We were kind enough to the leave the gate between our fences open in case their dc kick the ball over. Put this is taking the piss. She didn't even ask me.