It was decided to run the new side through the Metropolitan Union, a sub-union to the main body to keep it separate from clubs.
It was an experiment that has worked well worked well.
In season one, Metro finished third behind Massey White and Whanganui High School, then were runners-up behind WHS in year two before winning last season.
While some call the Colts grade U21, it's actually open to U23 with weight restrictions.
That, of course, means some players are forced to move on each year.
"This season were had a small core of older players, but by far the most have been younger, inexperienced guys," Cosford said.
"They have had an awesome season for such young players and even in the semifinal last weekend they never gave up. Despite being down by a wide margin they were still battling away at Massey's line in the last five minutes. Even the older guys praised the younger ones for their determination.
"Russell and I have said right from the start we'd give three years and the young ones immediately committed again for next season after the semifinal. We approached the St Johns Club too and they are keen to continue sponsorship. I think we will be a force to be reckoned with next year. We have some real talent to build on and we are all looking forward to it," Cosford said.
Several stars have emerged from the Metro team over the years.
Te Rangatira Waitokia starred in the Whanganui and New Zealand Heartland backlines. In fact, he was an integral part of the Whanganui team which narrowly won the 2016 Meads Cup.
Hare Meihana is another to catch the eye. Meihana played in the 2016 Whanganui U20 team that competed in the Hurricanes development series and was voted player of the tournament.