'Sometimes those who challenge us the most teach us the best': AP McCoy leads tributes to Richard Johnson

Richard Johnson finished second to his friend and rival AP McCoy 17 times in the jockeys' championship before winning it four times. 

AP McCoy expressed his gratitude to his old friend and rival Richard Johnson following the retirement of the four-times champion jockey.

McCoy has repeatedly insisted he would never have set the records he managed in his career without Johnson pushing him all the way.