Welcome Wren.
Please can you try to add another pic.
Your first is very small and sideways...will not enlarge for me to see the detail of the leaves.
At present I would guess a Salix sp...a willow....but that is just a guess!
Greetings, welcome to the Forums.
I concur, this does look like a Willow (Salix). Its probably long gone by now, but an interesting idea would have been to espalier it along the fence.
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