In their post-royal careers, Harry and Meghan have learned two lessons in quick succession: firstly, that membership of the royal family opens the door to media deals less well-connected celebrities could only dream about.

Secondly, they have learned that even royal fame will not, ultimately, help one of the biggest media organisations in the world sell a product that the public finds unappealing.

No doubt Meghan thinks mightily of the concept of Pearl, her proposed animated Netflix series in which a 12-year-old girl is inspired by great women in history. But it seems potential viewers are rather less enamoured. Netflix has cancelled the series before it was even made.

Considering the pair’s Oprah Winfrey interview was one of the biggest global television hits of last year, this must come as a bit of a shock to Harry and Meghan. But it must gradually be dawning on them that the world is only really interested when they are spilling the beans on the royal family. Take that away and they become a rather dull pair spewing out woke platitudes.

Pose as a spurned princess supposedly cast aside by a family given to the odd racist remark and people will tune in by the millions. But there will always be something far more interesting on another channel than Meghan Markle trying to tell us that we are all fantastic.

Anyone who thinks that Harry and Meghan have good commercial value beyond the context of their fallout with their respective families should try this little thought experiment. Ask yourself two questions: firstly, did you watch Harry Meghan’s Oprah Winfrey interview? And secondly, were you looking forward to watching Pearl? It won’t seem too much like a magic trick if I tell you that your answers were: ‘yes’ and ‘no’ – or perhaps more likely ‘yes’ and ‘what the hell is that?’.

The tragedy of Harry and Meghan is that their post-royal careers are really just a hyped-up version of Prince Edward’s career in TV. Edward began just as Harry and Meghan are trying to do now: with his company Ardent Productions making worthy, insipid programmes such as an interview with Nelson Mandela, followed by Edward’s own hobby horse, Real Tennis. But he only started to enjoy modest success when he started to cash in on royal programmes for the US market. Just about the only programme anyone remembers him for now is his infamous It’s a Royal Knockout, which attempted to revive an outdated programme format with royal characters – and I suspect people only watch that on YouTube to see if it really was as embarrassing as folklore would have it (to save you the time, yes it was).

Edward was reported to have been paid a £250,000 bung by the royal family to give up his TV career when Ardent went bust in 2009 and to become a full-time working royal.

Will it come to Harry and Meghan accepting a similar incentive (assuming they don’t burn what remaining royal bridges they have available)? The fate of Pearl certainly suggests that could be the case.