Crow or raven?

There are a pair of large birds that visit our grass field regularly.

It is hard to gauge their size as they are usually on their own.

The 2 photos below were taken a couple of days ago.  i have been unable to get any photos which show the tail in flight.

I have added below the only photos I have that would allow a comparison in size to another bird.

Here the bird is with a pheasant - but this could be a different bird, as I think these photos were taken last year.

There are ravens in the area, or are these crows?  Thank you.