Having pulled out of the top division due to the impending loss of a number of senior players, the Scottish club successfully applied to enter a development team.
They will be joined in Division Five by two clubs who also have development of young players very much as a priority - City of Leeds and Tyldesley. Both are returning to BWPL after a few years' absence having rebuilt their squads from scratch.
In addition to Portobello's Division One side, 2nd City Birmingham have also resigned from the League. But the addition of Portobello, Leeds and Tyldesley means that the lowest division will begin next season with a full complement of eight sides.