Sorry, "news" reporting? From memory, the headline is "Nuttall denies lying". Which rather proves the point that the Guardian is suggesting he IS lying.
Well, was he there or not? That is the real story. I suggest if the Guardian's intrepid and renowned reporters had proven he wasn't there...
I have no idea if Nuttall was or was not there, and don't care. But the Guardian has lost the plot in the last year or so, and should be read with caution IMHO. Not a lot better than the Daily Mail, just the opposite side of the political spectrum.