I think this Stanley Park tree is Acer palmatum, and I thought it might be a dissectum, but now I read that those are weeping and this is not (though I saw a photo of at least one dissectum that's not weeping), so I don't really know what it is. And, I don't remember what colour the leaves were during the summer. Our autumn colours have barely started, so this tree has the only red leaves around the area where it's growing. I thought the leaves might be distinctive. If I knew what it was, I could look to see if it's been posted in the photo gallery.
I didn't pick up on that from the drawing in Straley's Trees of Vancouver, but the leaves do have that shape, and Straley lists an 'Aconitifolium' at just about that location. It was called a "slender specimen" in 1992 when it was about 3 meters tall, and the description still fits, if that's the same tree. Thanks, danc.