United journeyed to the Boddington Football Hub for a re-arranged fixture five days before Christmas - and were beaten 4-1 by the Lions.
Substitute Nathan Bowen scored the Pilgrims' goal after half-time.
Boston: Daniel Martin, Oliver Fields (Finley Ging 53), Josh Doran, Will Langford (Joe Wilkinson 70), Ellis Perry-Burdett, Taylor Jaine, Jake Henderson (Rueben Fogg 70), Kris Zaluzinskis, Hugo Hunt, Lucas Turrell, JJ Ward (Nathan Bowen 46).