FWIW it's not a matter of predilection. Under the UK's work and immigration laws they can't hire writers/producers on a UK show unless they are at minimum a resident with a valid visa. (If it's a US show shooting in UK that's different.) Which is why I made sure to get one before moving to London.
J. Michael Straczynski
The BBC has always been against hiring American writers (or other countries outside the UK.) They had a 'new writers ' program over a decade ago, and when I tried to apply I was instantly rejected for being outside the UK.
