Blondiescot
The recipe is easily adaptable to feature any kind of pastry you prefer.
But being so adaptable is just what makes it the opposite of special or unique!
There is nothing specifically British or Royal about this quiche. IMO it has too many flavours, a hodgepodge of ingredients just like that dreadful Platinum Jubilee trifle year.
Scottish Salmon flan (hot smoked as in *Greydusters recipe) asparagus - English or Welsh, in season, or leeks (Welsh) and an English cheese would reflect at least three of the home nations, with perhaps Kerrygold butter to bring Ireland in?
Failing that - Welsh or English lamb, Jersey Royals (geddit) or Ayrshire potatoes, or Whitstable oysters - oh there are so many options they could have explored!
Or they could have chosen what I believe is the favourite takeaway - Chicken Tikka