The house in which the family lived is the house in which author John Mortimer and his parents lived, and where the author lived until his death in 2009. The gardening hat that Sir Laurence Olivier wore belonged to John Mortimer's father.
There had been an attempt to make a movie version with Sir Rex Harrison in 1973 or 1974, but after just a few weeks filming, it ran out of money. Edward Fox also starred, and he mentioned that none of the scenes he filmed involved Harrison. Apparently his agent was dubious that the producers had sufficient funds in place to complete the picture.
Laurence Olivier is a sighted actor playing a blind character. The part of a judge he pleads before is played by Esmond Knight, a blind actor playing a sighted character.
Clifford Mortimer quotes from stanza 9 of "Dolores" by Algernon Charles Swinburne (1837-1909): "Could you hurt me, sweet lips, though I hurt you? / Men touch them, and change in a trice / The lilies and languors of virtue / For the raptures and roses of vice;" Interestingly, this quote also turns up in Julian Mitchell's "Another Country", which also significantly features a boarding school.