When Alfred Hitchcock’s Psycho was released in 1960, it was with a strict condition attached. At Hitchcock’s insistence, latecomers would not be admitted to the film once it had started, a rule rigidly enforced by cinemas.

Given that Psycho starts out as a story about a secretary who steals money from her boss’s safe and hightails it out of town, before suddenly taking a shocking turn into far scarier territory, you can understand why he didn’t want the audience to miss a moment of the build-up.

Of course, Hitchcock had no control over what patrons did after they’d seen Psycho, but he did issue a request that people leaving the cinema not divulge the big, climactic surprise — one of the most celebrated in film history — to those queuing for the next showing.

History suggests the overwhelming majority complied with Hitchcock’s request and that Psycho’s secret was preserved for the enjoyment of generations of future viewers.

The chances of this happening with a major film now are next to non-existent. We live in the age of the spoiler, a term that didn’t exist when Hitchcock made Psycho. It first reared its ugly head in the decade that followed (apparently, one of the earliest uses of it was in an issue of National Lampoon in 1971), although it didn’t become common parlance until the 1980s.

Movie spoilers have been around forever, in the shape of the babbling idiot who insists on telling you every detail of a film you planned to watch. But TV spoilers are a different beast.

Before the internet, before even home video recorders, there was no such thing as a TV spoiler. We all watched television programmes at the same time and discussed them afterwards — therefore nobody could spoil our enjoyment in advance.

This went for TV critics too. In a time of slower media and longer deadlines, they’d watch something as it went out, just like any other viewer, and write about it for the next day’s paper. Now, of course, people have the means to watch their favourite TV programmes at any time they like, while TV critics get previews. Both can be a blessing and a curse.

HBO gave a number of critics, including this one, the first four episodes of season four of Succession a couple of weeks ago, so we already knew the momentous surprise that was coming.

We weren’t about to share it, though. Any critic giving spoilers for Succession or any other HBO series would immediately find themselves blacklisted by the broadcaster — and rightly so. To be honest, I don’t know of any critic who’s ever done it.

After a programme has been shown is a different matter, though. Once it’s been broadcast, all bets are off and critics are free to share as many details as they want.

In the case of Succession, which is simulcast by HBO in the US and Sky Atlantic here and in the UK at 2am our time, a few newspaper reviews appeared within minutes of the episode ending. More, including my own, followed as the day went on. All of them carried spoiler warnings for people who hadn’t yet watched the episode.

Nonetheless, Twitter was soon ablaze with complaints that the critics from the newspapers had ruined their enjoyment with spoilers. This begs a question: if you don’t want your enjoyment of a programme you’ve yet to watch ruined, why look at Twitter in the first place when you know you’ll be walking into a minefield?

And if you must look at it, take the advance precaution of muting the names of the programme, the characters, the actors and any other words with the potential to cause you to accidentally stumble over a big, fat spoiler.

When does a spoiler cease to become a spoiler anyway? At exactly what point is it considered acceptable to reveal plot details of a TV episode? A day after it goes out? A week? A month? Longer? Some people would say the answer is “never”.

Frankly, that’s just silly and unrealistic. Imagine if we couldn’t talk about the final scene of The Sopranos for fear of upsetting anyone who’s been planning to watch the finale since 2007, but hasn’t been able to find the time to get around to it.

As for the lone viewer who doesn’t yet know season nine of Dallas was a 30-hour dream Pamela had, boy are they in for a shock when Bobby turns up in the shower!