The pair's romance was thought to have filled the 18-month gap during which he was separated from Ono in 1973 and 1974, but Pang insists they were physically involved for almost seven years.
She says, "It wasn't a fling. We had a 10 year relationship and it was physical for six or seven of those."
And Pang, now 54, remembers Ono's alleged request she "look after" her husband when their marriage faltered in 1973.
She says, "She didn't know. Obviously she does now."