Well Hugo as a fairly experienced Captain who was once a fairly experienced F/O I have to agree with Mr Carn, you may be able to fly the aircraft as well as, perhaps better than, the other guy but there is a big difference between sitting in the left seat and the right.
It's not rocket science by any means but I am sure that any recently promoted Captain would confirm that the two jobs, whilst outwardly similar, make quite different demands on you. At the end of the day airlines don't pay skippers £20,000 a year more to do the same job.
Sounds like the Air2000 F/O did a good job, not as easy as it appears to be suddenly flying solo and in command of an airline jet with 200+ pax. and 7-8 crew on board. Don't think I would have come clean about the problem until we where on the ground but that's window dressing really.