England's players had to learn how to talk about their feelings during "honesty sessions" before the World Cup, says Billy Vunipola.

The psychologist-led sessions were aimed at erasing the mental scars of the 2015 World Cup when hosts England bowed out at the group stage.

Coach Eddie Jones, appointed after that 2015 campaign, set up the therapy.

"Men don't know how to talk about their feelings. It took us a while but we got there in the end," Vunipola, 26, said.

England endured a miserable World Cup on home soil four years ago - exiting after successive defeats to Wales and Australia, the first time a host nation had been eliminated at the opening stage.

"Eddie has definitely got the baggage out. It was something that was very important to us and it has probably freed us up a lot in terms of our relationships," Vunipola, who was part of the 2015 squad, said.

"Being brutally honest can hurt a few feelings. It was really good. She (psychologist Corinne Reid) gave us the platform to do it.

"It helps to listen to each other and care about another person's opinion and take it on board, rather than going back to your room and having a little moan to your mate."

England have kicked off their 2019 World Cup campaign in Japan with comfortable wins over Tonga and the United States. They are next in action on Saturday against Argentina.