Hi Nigel, I think you might be right regarding a lower quality stream. It was peak viewing time when we watched it.
I tried the same episode via the PC this afternoon and the quality was good. I'll try it again via the BT Box some time during the day just to prove one way or another.
Thanks
@DelicaMan Prime seems to have some pretty strange traffic management and it seems as if different devices have different priorities on their servers..
Definitely streaming issue, good clean picture this afternoon. Thanks all.