Maybe his 'coke shame' issues that were in the tabloids a few years back. The Yanks do not f*ck around about drug taking foreigners.
this, I mean the first thing you should do when you know your going to a country that requires paperwork for entry is sort it out, he could pay someone to do it ffs.
The only thing UK citizen needs to go to the US is get his ESTA authorization, which is done online in 2 minutes and is for 2 years I think - so it is possible that he forgot to renew his. Another theory is that they didn't let him in because of his history of coke use, which is what they did with Nigella Lawson (a famous TV chef in UK), after she was forced to admit to using coke in a trial she was a witness at.
He is doing work for a UK channel - I assume he has done work for them before - shouldn't it be equivalent of any normal business trip which people undertake all the time without having to do any paperwork - I have done it many times
Dunno your personal circumstances/work situ so cant comment. I do know that you Brits have a "special relationship" with the US, perhaps it is easier for ye. For example ye have 180-day visa waiver, we Irish only have 90.
Probably to do with the channel who employs him, they'd be the ones sorting it out in yet another proud moment for them