Really, what role’s next for you — a soulful Roomba that magically becomes self-aware? An unstable teen who doesn’t realise he’s actually 50-years-old? Ronald McDonald: The Movie?

Depp’s career scampering down Eccentric Highway has finally flipped over and rolled to a stop at Weird Boulevard.

After playing a dead scientist in Transcendence, a Carpenters-era vampire in Dark Shadows, a singing wolf, the Mad Hatter, Hunter S Thompson and Jokes-With-a-Dead-Bird-on-Head (in the megabomb The Lone Ranger), his resistance to normalcy is growing tiresome.

The latest Depp bomb, Mortdecai — an alleged comedy about a moustache and the ninny who wears it — continues to dismantle the myth that the actor is one of the world’s biggest box-office attractions.

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No: Jack Sparrow is one of the world’s biggest box-office attractions, and that act has long since grown stale, too, though Depp is making yet another Pirates escapade.

He’s also doing an Alice in Wonderland sequel. Hey, why not The Tourist 2 while you’re at it?

Depp needs to take a deep breath and realise that “manic man-child” is not a good place to be at 51-years-old. A dignified drama, or a debonair Cary Grant-style comedy, would better suit him than the capering and clowning.

Depp is a skilled actor who has an admirable bold streak. For years, it was impossible to imagine him starring in, say, Pirates of the Caribbean 5: SpongeBob’s Revenge, much less Mortdecai, an unfunny English sex comedy so devoid of wit that it makes The Lone Ranger look like a Noel Coward piece.

Now the contrary nature of Depp’s choices — the more freakish and less handsome, the more he likes the part — is starting to seem like a form of career Tourette’s.

Yeah, we know he can play flakes and nut jobs. But he has only a few years left of enjoying leading-man looks before he’ll be stuck playing Jennifer Lawrence’s dad. Why not deliver movie-star glamour?

Do something that’s really challenging — quietly carrying a picture as a detective or a soldier, like Harrison Ford or Humphrey Bogart used to do? Only occasionally has Depp even tried to play a relatively relatable human, and he’s never quite brought it off, at least not in a film that really connected with audiences.

Maybe Depp makes the choices he does because the success of his career feels deeply odd to him — in the words of his idol Hunter S, “When the going gets weird, the weird turn pro.”

But, at this point, the most radical thing he could do would be to play a normal person.