Actor Allusion: Ben Theodore apparently won a Laurence Olivier Award for his performance in an angsty stage production. As did Iwan Rheon, the actor who played him. Although the character otherwise seems to be a fairly straightforward expy of Ben Whishaw.
Speaking of Whishaw, in series two Simon gets cast as Ariel in Ben Theodore's production of The Tempest. The same role Whishaw played in the recent film.
The Character Died with Him: Geoffrey Hutchings, who played Simon's grandpa, died after the filming for series 1 finished. In series 2, his empty armchair remains in the living room until it gets set alight by Simon's disgruntled conquest and it's heavily implied that his grandma's constant cheeriness and obsession with minutia is a way of dealing with the grief.