"Foreign dynasty needs stronger local branding, commissions elaborate content tying itself to beloved national mythology" could almost be a communications strategy written today. Merlin's Cave is just an unusually expensive 18th-century version of it.
Queen Caroline turned King Arthur into an 18C royal PR strategy
https://theconversation.com/how-queen-caroline-turned-king-arthur-into-an-18th-century-royal-pr-strategy-288244