I can't be sure but I think it is a pochard. There were no obvious markings or colours apart from its beak which I think is a tell-tale sign.
No interactions present.
I was really unsure so thank you to Mark_at_Magdalen and Greg888 for agreeing with my identification.
Lat/Lng: 54.5303, -5.699
OS grid ref: NW607212
Widfowl and Wetlands centre