Experts on small mammals?

Yesterday morning I heard Tasha barking like crazy out on the gravel drive. SHe was dancing around something on the ground that was trying to attack her, though I couldn't at first see what it was. When I went out I found this small creature, about a 6 inch long body with a furred tail and a longish face. It was screaming at her very shrilly, but did not seem able to run away. It had VERY sharp teeth and claws. So I scooped it up into a deep plastic box, covered it with grass and hay and put it in my shed to see if it would recover movement. A few hours later it had made itself a nest in the hay and was curled up but very much alive. I put a saucer of water and one of chopped raw liver in the box and left it overnight. This morning it was running round the box, though had not eaten much. So I have now let it go in a corner of a field and it burrowed its way through the grass.

But what is it and how did it get here? The cats were scared of it and I think it would have bitten them hard, so I do not think they were responsible. Tasha would definitely not go near it, and she doesn't hunt small creatures. But it was definitely in shock and could not move when I found it. So the most likely explanation I can think of is that it was dropped by an owl or kestrel, and suffered shock and bruising.

I think it is either a stoat or a weasel, and I can only hope that it is old enough to fend for itself. It would certainly not survive if I had kept it, and there is no wildlife refuge within 100 miles of here. So I can only say Godspeed little creature, I hope you make it in the wild. Here are some pix of it - anyone who knows what it is please tell me.

He was very small - body barely 6 inches long, and no black tip to the tail, which makes me think weasel rather than stoat. But he may have been very young, so it is difficult to be sure. I just hope he was old enough to hunt.