Canberra's immediate release of English half George Williams after his position at the club "became untenable" leaves the Raiders with a healthy halfback cache that could turn the player market on its head.

Williams has been granted a compassionate grounds release from the final 18 months of his Raiders contract, which is believed to be worth around $600,000 a season.

The 26-year-old raised homesickness issues with Canberra management at the start of May, he and his expecting partner struggling for some time with the isolation from UK-based family due to COVID-19.

Following repeated requests for a release at the end of the 2021 season, Williams texted Canberra officials on Tuesday morning informing them his ongoing struggles were mounting and that he was not in the right mental frame of mind for training or Saturday's clash with the Roosters.

By mid-afternoon both Williams' agent and the Raiders decided the Englishman's release needed to be expedited in "the best interests of both parties".

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Williams took to social media on Tuesday night to say he texted the club about his mental state rather than to request an immediate release.

NRL.com understands the Raiders rapid escalation of his exit shocked Williams and his family, though was made by Canberra officials on the basis that his situation would not improve after several weeks working through the issue.

"I text to explain my mental well-being to the welfare manager?" Williams wrote on Twitter.

"I asked for a release weeks ago for the end of the season... Not once did I ask for a immediate release but instead of supporting me the club kicked me out the door."

Williams' return to the UK will be finalised over the next week, with Super League side Warrington believed to be the front-runners for his services ahead of his old Wigan outfit.

It is unclear if Canberra will look to place a transfer fee on Williams signing with any English outfit, having paid their own six-figure sum to secure his move from Wigan in 2019, which also gave the Warriors first rights to negotiations should he return to his home country.

The decision to part ways with Williams leaves the Raiders with a reasonable amount of salary cap space to target a halves replacement next season.

While Adam Reynolds (Brisbane) and Mitchell Moses (poised to re-sign at Parramatta) were the two biggest fish in a revolving playmaker's market, the likes of Shaun Johnson, Anthony Milford, Matt Moylan, Corey Norman and Ash Taylor are all yet to confirm their futures beyond this season.

Off-contract Storm utility Nicho Hynes looms as another potential option given he played his juniors in the halves.

Canberra has previously expressed little interest in ex-Dragons captain Gareth Widdop or former Raider Blake Austin, both of whom are looking to return to the NRL.

More immediately, Sam Williams moves into the No.7 jumper with Jack Wighton, Josh Hodgson and Jordan Rapana all returning for Saturday's 2019 grand final replay against the Roosters.

NRL.com understands there is no issue between George Williams and Canberra's players or with coach Ricky Stuart.

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Instead the COVID-19 pandemic has taken its toll on Williams and his partner Charlotte Lewis, who are expecting their first child in a couple of months.

Plans for the couple to return to England last year, and have family visit since his arrival at the Raiders were scuppered by travel restrictions, while border closures meant Williams barely saw his own Australian-based father Peter despite him living in Perth.

"George and his partner have asked on a number of occasions for a release to return to England to be closer to their families and we’ve decided to grant their request," Raiders CEO Don Furner said on Tuesday.

"George withdrew from training today and from the game this weekend which highlighted to the club the seriousness of George’s request.

"Over the past several weeks we have supported George and provided him with the best welfare support we could, however as a club we felt that his position at the club moving forward became untenable."