The drama (presenting information from a 2channel posting included in the book) claimed that Benoist is the only tea company to hold a set of three Royal Warrants, specifically by the Queen, the Prince of Wales, and the Queen Mother. However, there is no evidence to support this claim, and a search of the Royal Warrant Holders Association website reveals this to actually be true of R. Twining & Co.
The drama's assertion about Benoist's Royal Warrants lacks proof, whereas an investigation of the Royal Warrant Holders Association website reveals that R. Twining & Co. is indeed a holder of three Royal Warrants.