Writer David Renwick actively wanted Gill to be American, as he likes writing in the American idiom.
The locations department had roamed far and wide to find a property to act as Gil's house, but it was eventually found by the producer Verity Lambert, close to where she lived in Totteridge, and within easy reach for filming.
The theme tune "Alley Boogie" was chosen by the writer David Renwick because he a) listens to a lot of jazz and b) thought Alice's colleagues' nickname "Allie" for her made a pleasing match.