I’m not good at tree identification but I think this is most likely a Hybrid Black-poplar (Populus x Canadensis agg). It’s growing in a local park alongside the river – they like wet landscapes, and are frequently planted in parks and gardens but have also become naturalised in much of Britain.
What caught my attention with this tree was not the leaves or the bark or the shape but its seed fluff, which is so abundant at the moment that it’s covering the nearby path like snow in summer.
Poplar trees are dioecious, meaning there are separate male and female trees, and you can tell this one is a female because it’s producing the seeds, with all that fabulous white fluff attached.
