Detailed reports of the accident, inquest, and funeral appear in the Beckenham & Penge Advertiser 22-Jun-1899 pp5c & 8d, and in the Beckenham Journal 24-Jun-1899. PM me with an e-mail address for copies.
It appears that he and business partner Mr Banton had been building up a cycle-making business for the past year, and Mr Marchant had entered the open half-mile handicap at the Civil Service Supply Association Sports on the Herne Hill track to promote the business. Running last (which suggests he wasn't a regular racer) he attempted to overtake the man in front, collided with him, and was thrown off his machine, sustaining head injuries from which he died 6 hours later. He initially refused medical treatment, which the Coroner pointed out was unwise in the case of head injuries, but no one was to blame for his death. He was buried at Reigate on 22-Jun-1899.