Though the year of the action is never stated, the radio newsreader reporting the election result gives the date as 15th October. This must be a Friday, as UK General Elections are always held on a Thursday. The fifteenth of October fell on a Friday in 1993, which would tie in with the apparent ages of Princes William and Harry (though not with the Queen Mother claiming to be 92; she turned 93 in August of that year. Possibly she simply forgot).
Oliver Chris, who plays Prince Charles, previously played his son Prince William in King Charles III (2017).
Based on the book by Sue Townsend
Prince Philip and Princess Diana do not feature as characters in this adaptation despite doing so in the novel. Diana is not mentioned by name but only in passing as Prince Charles' "ex-wife" and Philip is not mentioned at all. Presumably the omission of Diana from this was a mark of respect given her tragic death in a car accident in 1997, which drew a huge public reaction. In the novel, Diana is drawn to a local man after Charles is imprisoned and Philip sinks into depression, refuses to get out of bed and ends up in a psychiatric ward.