One told, I think, by either Keith Waterhouse, Jeffrey Bernard or Alan Watkins.  Doesn't matter.
Concerns John Pilger, under heavy fire in somewhere like Beirut, back in the day when it was never out of the news.
Pilger is sheltering beneath a table, bullets flying everywhere, plaster coming off the walls and ceiling in chunks, the crump of mortars in the distance. 
Chap crawls toward him...  Can he take an urgent 'phone call from London?
Pilger dutifully leaves shelter, gets to 'phone.
'Er, sorry to bother you, John, it's Sharon...  would it be all right if I cancelled my dental appointment on Tuesday and made it Thursday instead?'