Mr Mustard doesn't look tribunal decisions other than for Barnet but sometimes he stumbles over ones that are interesting, like this one. 6 December was a Sunday so the days on the sign are relevant.
Why TfL fought the Appeal is unclear as a motorist wouldn't make up a story about sign changes as they are all logged by whoever erects them. Also, they have all been photographed by the google streetview car, and others, and clearly this sign has been changed at some point.
Costs are rarely awarded but the adjudicator thought that the high bar had been reached on this occasion.One can only hope that the effect of a modest costs order will make TfL more particular about facts in future.