But The Guardian reports that Premier Rugby chief executive Mark McCafferty is not pleased with the possibility of the EDF Energy Cup being used as a testing ground for three further variations that see most offences reduced to free kicks rather than penalties.

"It is not fair on players or referees to have one set of rules one week and another lot the next," he said.

The trials will apply in an as-yet un-named northern hemisphere competition, and the RFU, WRU and tournament broadcaster BBC will all have to agree for the EDF Energy Cup to be used in this manner.