Maybe it was nerves. I've been physically sick many a time when nervous, my high school induction day 8 years ago for example, the day of my interview for my current Saturday job for example. It wasn't flu (as it only came on just before having to go in most cases and went away soon after), but I was still sick.
Isn't a great impression to make though is it? This is why I would never try out on the apprentice (other than me not being business minded or particularly clever, not that it stopped Lee), it gets in to the papers and your reputation is in tatters.
Ten years down the line he could be earning twice his initial sallary, have a few holiday homes and a company car and be extremely successful (hey, Sir Alan managed it) and still he'd have people bring up the fact that he lied on his CV or that he was ill on his first day.
Whereas if he'd applied for a job at Amstrad the proper way, he could just move to another business and no one would be the wiser.