Interviewed for a new book marking the 25th anniversary of its release, McKidd reveals he was promised he would be used in posters and other promotional material, but was left feeling “pretty raw” at this treatment.
McKidd has one of the key roles in the film as Tommy, the fitness fanatic who turns to drugs after being ditched by his girlfriend.
The actor has never had an explanation why he was dropped from the £850,000 marketing campaign, saying: “It was a hard thing to get your head around.”
McKidd reveals he was left furious after discovering he had not been invited to the film’s lavish launch in Cannes.
Jay Glennie has interviewed author Irvine Welsh, director Danny Boyle, producer Andrew Macdonald, screenwriter John Hodge and key cast and crew for the book.
Glennie recalls how Ewen Bremner, Robert Carlyle, Kelly Macdonald, Ewan McGregor and Jonny
Lee Miller were flown to London the day after filming wrapped for a photo shoot with each actor still in character. However McKidd had gone straight to Tunisia on holiday.
He tells Glennie: “What happened was I had booked a holiday and told them all but was told not to worry as they were going to use single shots for the posters, and that they’d be in touch and set something up for when I returned in a week or so.
"No problem. I went away to enjoy my cheap holiday.
"I never heard a thing. The honest truth is I still don’t know what happened.
"I told the press at the time that I went on holiday and missed it and kinda played the patsy to let the truth be THAT, but the fact is I don’t really know what happened. It was all very weird. I just don’t why I was never invited.
“It did bother me for a few years after, particularly because it would be one of the first things people would ask me about. It was a hard thing to get your head around."
McKidd recalls having to walk back to his Glasgow flat in the ran following the premiere party because there was no transport available and eating a fish supper off his lap on the night of the Cannes premiere.
He tells Glennie: “To be totally candid I sat there and thought ‘What the f*** happened?’ I’d missed the poster shoot and now my invite to Cannes must have gone astray.
"I had had a great experience shooting the film. I was safely tucked away and then it was the executives making the decisions that tainted things a little for me.
"Over the passage of time that’s diluted, but it was pretty raw at the time. I’ve never revealed that and how I felt. I was a young actor and so incredibly grateful to the film and didn’t want to be seen as bad mouthing it in any way.”
Pauline Lynch, McKidd’s on-screen girlfriend Lizzy, is among the cast interviewed for Glennie’s book.
Looking back on the film, McKidd says: “I can talk about Trainspotting now because it doesn’t sting anymore.
"I loved Ewan, Danny, Irvine, Ewen, Jonny, Bobby, Kelly, Pauline, everyone.
"But my experience because of the place I was in at the time, just so socially anxious, wasn’t glowing, so it has been great to look back on it now.
“When Trainspotting became a great hit, pals were saying to me that I should get over to Hollywood and chase the dream, but my gut told me that it wasn’t my time. I was in no way ready.
“I was so green and I knew that LA would chew me up and spit me out. I made that decision to bide my time and to continue to work. Trainspotting opened doors for me, of course it did, but it took another fourteen years before things started to happen. Rome and Grey’s Anatomy, they were my time to pop.
“Making Trainspotting was a fantastic experience and Danny’s passion and his innate ability to create a great chemistry on and off set helped me grow as a person and actor.
"The film blew the f****** doors off and I am so bloody proud to have been a part of it.”