Who stipulated ?

Another tricky one for BBC News and Zarin Patel on staff and company status; this from Fiona Bruce, interviewed in The Independent....

"I formed a service company because it was a stipulation laid down by the BBC. And I pay my full share of tax." So, you pay the 50p tax rate? "Yes." So why have all the embarrassment of a PSC? "It's a stipulation that I, and a number of other presenters, have to form service companies to be employed by the BBC. It's not my choice, and it would never be my choice. But that's the situation."