London: the mounted Horse Guards at the Wellington Arch

Does anybody know at what time it's possible to watch the mounted Horse Guards at the Wellington Arch (Hyde Park Corner) on next sunday ? Thanks again.

The Changing of the Queens Life Guards (Mounted on Horses) continues to take place daily at Horseguards, at 11.00am Mondays to Saturdays and 10.00am on Sundays.

Taken from: http://www.changing-the-guard.com/sched.htm