boundary hedege and shared garage wall

Hi

Two questions in one !
1. We have a hedge that runs down one side of our back garden. It seems to be the boundary between my garden and our neighbours garden. It isn't clear who owns the hedge as it runs along dead centre. Can my neighbours remove this hedge and replace with a fence without my permission?

2. We also share a common garage wall with this neighbour. There is a large crack running along said wall and we will most likely have to rebuild part of it when we convert our garage. Again where do we stand with this if its a shared wall?

Hope that makes sense!

1. Strictly speaking you would need your original land registry maps and a good engineer to establish whose is the hedge- is it on your land, is it on your neighbours land etc. If it is on your land your neighbour has no right to touch it and vice versa. If it is a shared hedge then they should get your permission to remove it entirely.

2. There is a big crack in the wall- but presumably it is fine for a garage- is it? Is it something that would need to be touched if you weren't converting your garage? I'd say if you want to convert your garage and you need to rebuild this wall you should approach your neighbour, ask their permission to do this- pointing out that you will be perfecting it and only then go ahead.

Lets assume its a shared hedge - and we didn't want to remove it - where would be go from there (hopefully that wouldn't happpen as we want good neighbour relations! - its just a hypothetical at this stage)

Re the crack we have been told it 'would outlive all of us' so its fine as a garage but I think if we wanted to convert it or build on top then we would need to look at it.
What would happen in the case where they wanted to refuse ?

Thanks