Born in Nuneaton, Warwickshire, Gerard Francis Anthony Manby-Colegrave entered his MG Magnette K3 (K3004) in the Junior Car Club 1000 mile race at Brooklands in 1932. Run over two days he teamed up with P. M. Walter, but they lost two hours early on after needing to change a head gasket. He also raced an Aston Martin in the Autumn BARC Meeting at the track, entering the 500 mile end of season race. Unfortunately he retired with a cracked sump.
He finished 3rd in the MG at the second British Empire Trophy at Brooklands on July 1st 1933 when, in the closing stages, Oliver Bertram, who was running third, had to retire when the crown wheel failed on his Delage. This allowed Ron Horton to move up a place but a misfire then allowed Manby-Colegrave past to take the last spot on the podium. He also finished 7th in the International Tourist Trophy Handicap race held at Ards-Belfast.
He helped found the Squire Motor Company in 1934 when he and Reginald Slay joined up with Adrian Morgan Squire, working together from a filling station and workshops at the top of Remenham Hill just outside Henley-on-Thames. By the summer a prototype was running and was soon offered for sale at £995. Several bodies were offered, including the lightweight "Skimpy" as well as some by Vanden Plas. Sales were slow and four cars were registered to the directors. The price was cut to £695, similar to an Aston Martin, but the launch of the Jaguar SS100 was too much and the factory was forced to close.
He took third in one of the Mountain Handicap races at the Easter meeting in 1934 and traveled to Ireland for the Cuairt Bhre road race in May. He was the lone British entry but he was sidelined by valve trouble while running in a strong second place behind Frank Gannon’s Lea-Francis. He did however set a new lap record during the race, a record that still stands as this was the final time that cars raced there.
He had the MG re-bodied in time for the Easter meeting at Brooklands in 1935 and also entered a '4.9' Bugatti for Dudly Froy to drive in the Senior Long at the same meeting. Jock retired from his race with gearbox problems.
For 1936 he switched to an ERA and took fifth in the Junior Car Club 250 mile International Trophy race which resulted in one of the closest finishes ever seen at Brooklands, with Bira crossing the line just 1 second ahead of Raymond Mays after a fine battle in the closing stages. He also claimed fifth in the RAC International Light Car Race at Douglas on the Isle of Man.
He made a rare overseas appearance in July 1936 when he traveled to Portugal for the Formula Libre race at the Circuito International de Vila Real. After qualifying in 4th spot he retired on the tenth lap with gearbox problems.