Answer
Who owns the fence between two gardens?
No automatic rule; the title deeds and Land Registry plan decide it, sometimes via a T-mark.
In short
There is no automatic rule, despite the common myth about the left-hand boundary. Ownership is set by the title deeds and the Land Registry plan, sometimes shown with a T-mark on the owner's side. Check your deeds, and where a boundary is shared, agree the work with your neighbour first.
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