“I wish our team the best of luck at Tokyo. I will be cheering them on.”
The showjumping competition at the Olympics is set to begin on Tuesday, August 3, with individual qualifying.
The individual final will follow on August 4, with team qualifying on August 6, and the team final on August 7.
Wordley had been set to attend his second Olympics, having previously competed in Beijing in 2008, while O’Neill will be taking part in her first.
She joins Bruce Goodin, a veteran of four Olympics, and Daniel Meech, who has been to two previous Games.
Tom Tarver is the new travelling reserve, with horse Popeye.