Northampton Casuals secured the Rugby League Conference East title with a 34-26 win over St Ives Roosters.
The Casuals came from eight points behind to maintain their unbeaten record this season.
Head coach Jo Smith told BBC Radio Northampton: "We are too good for this division.
"We were second from bottom last year, but we started training in March, and a lot of lads have made rugby league their first sport."
The club will now make a decision on whether to apply for North Midlands or Midlands Premier status next season.
"This club's got huge potential. In five years' time, National League Three is probably the least it deserves," Smith added.
Casuals chairman Andrew Quirk paid tribute to Smith and assistant coach Gary Campbell.
"They've brought quite a few players with them, and attracted some of the older ones to come back. The structure of the club has improved, and there's a lot more discipline," he said.
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