Felix Jones has quit his position as England defence coach less than a year after taking the role, according to a report in the Sunday Times.
The former Ireland full-back joined Steve Borthwick's backroom team after helping South Africa to retain their World Cup crown last October as part of the Springboks coaching ticket.
The Sunday Times reported on Saturday that 37-year-old Jones had made the decision to leave England, who finished third in the last Six Nations and lost twice to New Zealand during the summer, as he was "unhappy with an unstable working environment".
Jones' profile does not appear on the RFU's website.
The RFU is not expected to comment on the story today but RTÉ Sport understands that Jones is on a 12-month notice period.
Speaking ahead of the Six Nations in January, Borthwick said of his new coach: "He's one of the most intense people I have ever met, and if I can tell you that, it's saying something.
"Meeting with him, being on the phone with him, having a conversation with him for an hour, and not getting a word in because he has so much rugby knowledge, it is unreal.
"And a work ethic that is astounding."
Former full-back Jones played for Munster between 2009 and 2015, and won 13 Ireland caps.
Earlier this month, Aled Walters left the England set-up to become head of athletic performance with the Ireland men's team.
The uncertainty surrounding the England management team includes Kevin Sinfield, the rugby league great who was demoted to skills coach to accommodate Jones' arrival.
Sinfield was poised to step down after the recent tour to Japan and New Zealand but his popularity amongst the players, as well as his experience, was seen as too valuable to lose.
However, an extension of his stay and in what capacity has yet to be confirmed.
Jones’ desire to leave is understood to be linked to Walters’ departure, with the two forming a strong working relationship while serving under Erasmus with Munster and then South Africa.
But the churn of backroom staff – a destructive theme of the Eddie Jones era – also asks questions of Borthwick’s methods.
Attack coach Richard Wigglesworth, scrum coach Tom Harrison and coaching consultant Andrew Strawbridge are now the only confirmed members of Borthwick’s management team heading into the autumn.
The All Blacks’ visit to Twickenham on 2 November opens a schedule that continues with fixtures against Australia, South Africa and Japan and it remains to be seen if Jones will be involved.
Borthwick will see the development as a huge setback having repeatedly hailed the impact made by Jones, whose knowledge he has described as "groundbreaking".
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Additional reporting: PA
