WASPS stopped short of actually saying it, but they clearly feel betrayed following Billy Vunipola’s decision to leave them for Saracens this summer.

The 20-year-old told the club he was leaving less than an hour before Saracens announced his arrival and, it is understood, days after he signed a contract with his new club.

The news was a bombshell to Wasps, who assumed he was staying right up until the moment he told them otherwise.

The club had offered him the terms he asked for and claim that during negotiations the player himself insisted he wanted to remain with the black and golds despite rumours linking him with Saracens, where his brother Mako plays.

Director of rugby Dai Young said: “We are clearly hugely disappointed.

“Billy is a player that the club identified some time ago as one with huge potential and he’s been developed by Wasps, despite a period when he struggled with illness and injury, into one of the brightest young talents in English rugby.

“During our contract talks, the player had been adamant that he did not want to leave the club but we know he was under pressure for family reasons to go and join his brother at Saracens. We did everything in our power to keep Billy. We offered him the contract he asked for.

“He is playing regularly and he has already got international recognition, so we didn’t see any reason for him to leave.

“Although we had heard the whispers about him going to Saracens, we were only officially informed yesterday afternoon that Billy was leaving and he had previously signed for them.

“Although we are bitterly disappointed right now, it is only fair for me to say that I believe that Billy will become a top quality international player for years to come and we wish him the best with his career.

“There is a long way to go in the season and I am sure he will give his all for Wasps in the coming months.”