The reason I never doubt the honesty of an angler is I know, as a photographer, never to question the weight or, opening up a can of worms here, the species, as a picture can drastically alter the perspective of the fish.
Just take a look at the two images of recent barbel myself and fellow Nash man Chris Petter took. Which barbel looks bigger? To me Chris’s barbel looks far bigger, yet this is just down to the angle in which the photograph was taken. Chris’s barbel weighed 11lb 10oz while mine went 14lb 7oz!