Diamond, who has previously worked in Prem Rugby with Sale Sharks and Worcester Warriors, held the fort as Newcastle struggled to compete financially with the rest of the league.
They operated well under the salary cap and saw a string of homegrown players cherry-picked by other Prem clubs.
There were even worries that Newcastle would go the same way as Worcester, Wasps and London Irish, although Diamond, who had been at Sixways when Worcester went into administration, always insisted that would not be the case at Newcastle.
The club thanked the 56-year-old for his ‘passion, contribution and guidance’, external, but his departure comes as part of a wider restructure off the field at Newcastle.
McIlroy will arrive with experience from holding similar roles with French rugby league club Catalans Dragons and Top 14 outfit Clermont Auvergne.
On top of this, John Fletcher is to join on 1 December as the club’s new academy and pathways director, having been head of pathways with Scottish Rugby, while former Scotland captain Jonny Petrie is to become managing director from Monday, after he previously held executive roles at Edinburgh and Ulster.
