Woestijnvis is a production company like Endemol (only better
). They produce(d) such shows as Man bijt Hond, De Laatste Show, De Mol, De XII Werken van Vanoudenhoven, Alles kan beter, Schalkse ruiters, Mannen op de rand van een zenuwinzinking, Alles komt terug. Most of these formats (all original formats BTW) were sold to various Dutch TV stations, so you probably will have seen the Dutch versions of it. One which is on now is 'Alles komt terug'. It's on on Sundays, VRT TV 1, 20.30. It's pretty good, but not as good as we've come to expect from Woestijnvis.
As for the night of the proms: We've had them for years, and as far as I know, Heineken has nothing to do with it. In Belgium it's being sponsored by Stella Artois, so I HIGHLY doubt Heineken will want to have anything to do with it
As far as I know, Prince Philip (to get back to the original topic) doesn't have another job. He does go on a lot of trade-missions all over the world, but that'll probably be the same for your Willem-Alexander. He did serve in the Air Force, I believe as a fighter pilot (not sure if it was Mirage or F-16)