Is this a raven?

I've always tended to have been confused by the difference between crows and ravens. We certainly have many carrion crows flying around this valley as well as jackdaws whose differences are much more distinctive.

Recently I spotted two large corvids on the cabin roof and started to check online websites which purported to explain how to distinguish ravens from crows.  The two things that I resonated with me were the hopping nature of ravens and also their distinctive calls. However I often their their call but don't see them to check what they look like. 

This bird is I believe a juvenile raven and it certainly hopped like one. Its plumage is a bit less easy to differentiate. This picture was taken from my office of the roof of the garden cabin.

In the late 1970s for a few years I lived in Holland Park in London, between Notting Hill and Shepherds Bush. Our frisbee team called the Ally Pally Tossers would gather to 'train' and play together on the famous north lawn of the wonderful Holland Park, by the old 'magic' tree as it was called. Several ravens lived there and coped with all the human company. One day when I was throwing discs back and forth on a quiet spring evening, I heard a beating sound of flapping wings, and one of the ravens landed on my head. I had long hair in them days. It stood there for a short period, maybe for thirty seconds or more, while I stood looking at Nick my frisbee throwing partner, and then it flew away again. Nick was as amazed as I was. It didn't happen again, but I felt very privileged!