The scrum-half and prop – aged 28 and 27 respectively – have put pen to paper on deals that see the duo remain in Northampton.
James arrived at cinch Stadium at Franklin’s Gardens from Championship outfit Doncaster Knights during the summer of 2020, having also enjoyed spells with Bedford Blues in the Championship, as well as Loughborough Students in National One.
The No.9 has since impressed in Black, Green and Gold, with 25 points now on his tally from 27 appearances for Northampton.
Meanwhile Heffernan linked up with Saints back in February 2021, joining from Championship outfit Nottingham Rugby. The English-qualified prop originally hails from Clifden Galway in the west of Ireland, but came through the Leinster Rugby Schools set-up before making three appearances in the Pro14 for the senior side.
A hamstring injury sustained this season has limited Heffernan to only three appearances in a Northampton shirt to date, but incoming Director of Rugby Phil Dowson is delighted to see both he and James remain a part of his squad.
“We’re thrilled to see both Oisín and Tom recommit to Saints,” he said.
“TJ has been going from strength to strength since he joined us from Doncaster, and is thriving amongst the talented group of scrum-halves we have at the Club.
“And while injury has disrupted Oisín’s time with us so far, he has grabbed his opportunities with both hands and is really working hard to return to action as soon as possible.
“Both guys are very ambitious and popular members of the squad, and we’re looking forward to seeing them kick on in Black, Green and Gold.”