There are some scenes and sequences from films that insert themselves so indelibly into the collective consciousnes, that were every scrap of celluloid it was printed on shredded, every videotape used for kindling, and every DVD frisbeed off the edge of the world, the sheer magnetic energy put out by millions of people replaying it on their mind's eye could burn those scenes back into being on a reel of BetaMax tape.

Take for example the dawn helicopter raid set to Wagner's "The Ride of the Valkyries" in "Apocalypse Now". Or think about the Odessa steps in the "Battleship Potemkin". And don't you wish you could stop thinking about the "Squeel like a pig" scene in "Deliverance"?

And then there's the "Worst Toilet in Scotland" scene from Danny Boyle's "Trainspotting", based on the 1993 novel by Irvine Welsh, where a no longer constipated Renton, played by Ewan McGregor, is not only forced to brave the aforementioned toilet, but has to retrieve some lost "cargo".

Well, there's more where that came from. Director Boyle, whose Sci Fi film "Sunshine" is just opening, has told The Scotsman that all the actors from the original film have now signed on to do the sequel, based on Welsh's novel "Porno".

Danny Boyle

Boyle has [...] given the clearest indication yet that the original film's leading star, Ewan McGregor, will be reunited with fellow actors Robert Carlyle, Ewen Bremner and co, claiming that "all the actors" have agreed to reprise their unforgettable roles.

Boyle has long talked about his desire to bring Porno, Irvine Welsh's follow-up to the cult novel that spawned Trainspotting, to the silver screen. However, the project has long been shrouded in doubt, with McGregor reportedly insisting that he does not want to be involved.

The news has been described as "fantastic" by film critics and Scottish Screen, which says there is a massive public appetite for a follow-up.

It is widely held among film critics that Porno cannot be made without McGregor, and public comments from the Crieff-born actor have seemingly killed off the possibility of a follow-up. As recently as last week the star was reported to have said: "They can go ahead and do it if they want, but it will be without me on board."

He said he was "very proud" of Trainspotting and insisted he "wouldn't do anything to damage it".

"I read Porno and I didn't think it was as good as Trainspotting. There was nothing new in it," he added.

McGregor was furious with Boyle when he chose Leonardo DiCaprio to star as the traveller on a Thai adventure in The Beach, a decision the director has apologised for.

But speaking this week at a preview of his latest movie, the science-fiction thriller Sunshine, Boyle reiterated plans to bring Porno to the cinema and indicated that McGregor was on board.

So will McGregor's initial scepticism prove prescient, or is there still cinema gold to be mined from these plumbings?