Black Poplar

I have walked past this tree hundreds of times since I moved here 13 years ago. It suddenly dawned on me last week that I didn't know what the hell it was!! I'm good with trees. Normally have an idea.
This morning I have spent almost an hour finding out.
From my Wildflower Key reference book (used to do conservation work) I pinned it down to black poplar. Then I checked out the Woodland Trust site, and their standard was a completely different shape!

Not to be defeated, the internet was trawled. It is indeed a black poplar, but a cultivar or a farer subspecies.

Today, I have achieved :D