The Australian club ended speculation over Reilly's plans yesterday by announcing that he had agreed a two- year contract to coach them in the Winfield Cup.
Reilly, who spent five seasons playing for Manly in the early 70s, has long nurtured an ambition to return to Australia.
Only last month, however, he was adamant, in denying reports linking him with
another Winfield Cup club, Eastern Suburbs, that he intended to honour a Halifax contract that runs until 1996 and wanted to coach England in next year's World Cup as well as Great Britain in this autumn's Ashes series.
'The offer came out of the blue and it was an absolutely agonising decision to make,' he said.
That decision has thrown both his employers into confusion. There is little more than a month before the Australians arrive in Britain and the Rugby League must make up their minds rapidly whether to let Reilly carry on - as Newcastle are more than willing for him to do - or
appoint a successor.
Reilly, whose disillusionment over the delay in appointing a team manager and assistant coach for that series is thought to have played a part in his departure, said he had 'an open mind' on whether to carry on.
There is no doubt, however, that he would do so if asked. The League's chief
executive, Maurice Lindsay, returned from America yesterday and he and other members of the League's board of directors must think very carefully before adopting the stance of the aggrieved party and refusing to ask him.
They must ask themselves whether there is any feasible alternative. With the short time available, only someone well versed in Reilly's methods could maintain any continuity in a squad preparing for the Australians and that points irresistibly to Reilly's one-time assistant, Phil Larder.
Larder, now in charge at Keighley, left that assistant's job and the role of national director of coaching to join Widnes two seasons ago and the circumstances of his departure could count against him.
The names of Dave Topliss, involved with Great Britain over the years and out of a job since resigning at Wakefield, and of Ellery Hanley, associated with many of Britain's finest moments under Reilly, are also likely to be mentioned. Meanwhile, the Halifax board met last night to decide whether to go for a clean break or let Reilly stay on as a caretaker for his own successor.
'There's a bit of surprise and a bit of disappointment,' Peter Marsland, the club's director and spokesman, said 'We will probably take our time and cast our net wide for a new coach.'
Reilly has been at Halifax for a season and a half. His tenure in the Great Britain job is, at seven and a half years, the longest on record and, statistically, one of the most successful.