Hewitt's firearm was supplied by gunsmiths T. Stensby & Co. Ltd., whose premises in Withy Grove, Shudehill in Manchester were not too far from Granada Television's studios. The company remained in existence from 1810-2011.
When discussing Hewitt's mistress, Dimmock muses "O Moira! Shall I call thee Bird,/Or but a wandering Vice?" He's wryly misquoting the 1802 poem "To The Cuckoo" by William Wordsworth (the actual lines being "O Cuckoo! Shall I call thee Bird,/Or but a wandering Voice?").