According to J. S. Matthews’* notes which accompany this image, the two buglers shown in the middle of the shot used their instruments to ‘control the ride’, but he didn’t explain exactly what that meant. There are a couple of clues here and here, however.
There are some individuals who are identified by name. “Mr. Stark” is almost certainly William M. Stark (son of James Stark, owner/operator of James Stark & Sons Glasgow House), an early automobile and airplane enthusiast and a good amateur photographer. A thorough bio of journalist, William Francis Findlay, appears in WestEndVancouver. Charles A. Ross was an employee of the Begg Motor Co. E. S. Wilband would become a director of the Vancouver Athletic Club. Frank Ross Begg was one of the two brothers (the other was Frederick Bruce Begg) who owned Begg Motors.
“Mr Marshall” would seem to be Colin (John) Marshall, who appears in the 1912 image below. He was a broker by occupation and served in the armed forces in the Great War and survived, retiring as an officer in 1921. He died in 1950.