Titles of films John Barry was alleged to be scoring in the past, but that did not happen or scores were replaced. Several titles may have been be mere speculation at the time and hold no truth whatsoever.
Travels with Charlie
Barry bought the rights and planned to act as composer/producer with segments to be directed by people like Kevin C. I seem to recall that Jim Wilson might have been a co-producer? Not sure! Barry publicised this quite a lot in the sweep of post-Dances popularity but (obviously) it never arrived.
Worked on this for some time but apparently the studio did not agree with his take. There seems to have been a misunderstanding as director Brad Bird hired him on the basis that he would write a score which was a pastiche of his James Bond scores. Barry had no intention of scoring it that way and even his trailer music was replaced by a real Bond theme - OHMSS! They could not agree and Barry left.
Composer: Michael Giacchino
Thomas and the Magic Railroad
Barry was initially very enthusiastic about this (his son was a big fan of the stories) and wrote several songs with Don Black. However, he eventually decided the film was not going the way he had envisaged and left.
Composer: Hummie Mann
Tom's Midnight Garden
Director Willard Carroll wanted Barry (him being a big fan), made one phone call just to check out availability but there was never any discussion beyond that.
Composer: Debbie Wiseman
Wrote and recorded full score. However, the film's writer, Ron Peer, who was delighted that John was the composer, believes he did not want to "lighten" his score in certain places as required by the director during the editing process. Hence John Ottman was brought in to write a replacement score. It's worth noting that actress Ellen DeGeneres claimed that test audiences reacted badly to the film originally ending with her character being killed, so she was called back to re-shoot the ending.
Composer: John Ottman
The Horse Whisperer
Wrote and recorded several demo themes but disagreements with director Robert Redford led to him leaving the project. He did not compose and record a complete score, as has been suggested.
Composer: Thomas Newman
"I met with the director, Brian Gibson, and told him how I work. I would give him themes, and then I go off and work, and then go to Los Angeles, he's finished shooting, we spot the movie. I did a few things which he really liked a lot, and which Columbia liked. Then he said, "Well, what about the rest of the music?" and I said, "What about the rest of the music?" He said, "I want to hear it." I said, "This is not an audition, Brian. This is your second movie. If there's anything at the end of the day that you don't like, then we have a little session."
Composer: James Newton Howard