England defence coach Felix Jones quits in another blow to Steve Borthwick

Jones has been an important figure for England since his recruitment 10 months ago from South Africa, who he helped win back to back World Cups under the guidance of Rassie Erasmus.

The 37-year-old former Ireland international was responsible for introducing the blitz defence that was starting to bear fruit after some teething problems early in the Six Nations.

Its aggressive nature made an impact against New Zealand in July when England fell to narrow defeats in Dunedin and Auckland.

Although Jones has handed in his resignation, his contract reportedly contains a 12-month notice period that would keep him in place until next year if triggered by the Rugby Football Union.

News of his surprise departure comes in the wake of influential head of strength and conditioning Aled Walters - also a former Springbok hire - dropping an equally unexpected bombshell by defecting to Ireland.

Walters was an influential voice on the training field whose involvement extended beyond his fitness duties and he was joined through the exit door by Tom Tombleson, a long-serving member of the conditioning staff.

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 - also a theme of the Eddie Jones era - will raise question marks over 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 end-of-year internationals

The All Blacks' visit to Twickenham on November 2 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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