I live in Harrow. I have a 40 feet ash tree in my garden. Half of the tree is leaning towards the neighbours garden. I want to cut this tree down. Am I allowed to cut a ash tree in my garden?
so the trunk originates in your garden? If so then the tree is yours but it sounds like you would need to talk to your neighbour and do it carefully (or get someone to do it for you) so as not to cause damage to your neighbour’s property and to make sure that children and pets are kept safe while you are removing the tree. You will need to check that the tree has no preservation order (TPO) on it. Talk to your local council about this before you do anything. You can be fined for removing (or even pruning) a protected tree without permission.
In addition to checking for a TPO, if you live in a Conservation Area you have to apply for permission to lop, fell or prune any tree over a certain (very small) size.