Looking at pictures of common pochard they seem to have a red iris whereas this bird has a yellow iris, also this bird just doesn't look quiet right for a pochard, I'm not sure why. Thanks for replies so far.
The Pochard always has red eyes, with a dark bill with a whitish band to the central region of the bill.
The Redhead will always have yellow eyes, with a light blue/grey bill that as a black/dark grey tip on the bill.
Another obvious difference between Redhead and a Common Pochard is that the Reddish hood goes further into the breast on the pochard when in the water the hood is just above the water line with a pochard and on the Redhead it’s only just onto the shoulders.
Also the Pochard grey/silver back feathers are more pronounced as the Redheads are slightly darker.
The Pochard also as a slightly longer tail of which the black/dark grey feathers are more constant to the tail only were as with the Redhead the darker feathers do actually go into the body at the rear of the bird.
That's great, very informative, thanks. Now you've pointed it out I can see there is a clear difference in the bill colour. I could have done with your knowledge at Axe valley, there were some other ducks I couldn't identity and couldn't photograph. Their Zootierlist entries could do with a good update too.