Today, April 9th is Palm Sunday. It is the day that begins the most solemn season of Holy Week, and the day where the liturgical mood turns from the joyful entry into Jerusalem, to the story of the Crucifixion.
In the late 1970's, the publisher J. B. Cramer & Co. Ltd. began a series of publications entitled, "The Cathedral Organist." These publications were intended to be a yearly thing, and featuring the works of contemporary organists at various cathedrals in the United Kingdom. As far as I know, the project only lasted 2 years. I have both of these volumes, and this work comes from the 2nd set, published in 1979.
Timothy Redman was Organist and Director of Music at St. Mary's Cathedral in Glasgow, Scotland at the time of this composition. I've looked for more information about him, but other than coming across a number of people who studied with him, I'm sorry to say that I've found nothing else about him.
The "Intrada" sounds like an improvisation which would have been played at the beginning of the solemn liturgy of Palm Sunday. It is a processional-type work, probably conceived as music to be played as the choir and clergy make their way to the location to begin the service.
The theme of the piece is the Gregorian melody, "Laus et Honor," ("Glory and honor, and laud be to thee, King Christ the Redeemer") which would be sung during the processional entry.
The tune is first stated on the Solo tuba, and then harmonized in large chords, alternating with some short "toccata-like" episodes. The tuba makes another brief appearance before the end, and with the arrival of the last chord, the stage is set to begin the liturgy.
Several photos of St. Mary's Cathedral in Glasgow are attached below.