The England star had originally been due to sign for 2021.
James Graham says he’d originally planned to rejoin in St Helens next year, before a conversation with an old team-mate brought plans forward.
The England prop had been in line to link up with Saints for 2021, but long-time friend Paul Wellens convinced him to make the move early, after Saints lost Luke Thompson to Canterbury.
Graham told the Saints podcast: “I’d been talking to Mike Rush about the possibility of next year.
“That was a couple of weeks ago and the conversations were going OK, and then I was on the phone with Paul Wellens, who I’m still good mates with.
“We speak pretty regularly and on one of those occasions he asked – would I come this year – and I responded that it’s not as easy as that.
“But that planted the seed and a few conversations happened, and it all fell into place really.”
Graham also revealed the identity of the only other British club he’d have considered joining.
He confirmed: “There was St Helens or potentially Workington Town that I’d consider playing for if I came home.”
Graham is a patron of Cumbrian children’s charity Team Evie and his dad hails from Maryport.