Spalding took a 14th minute lead through Archie JONES, despite huge Boston protests for a foul, although Claudio OFOSU equalised three minutes later.
Ex-Pilgrim Lewis HILLIARD (63) and fellow substitute Dylan EDGE (82) ultimately put the match beyond the Pilgrims - despite Sam McLINTOCK scoring a sublime second for the Pilgrims with two minutes to play.
Spalding (4-2-3-1): Michael Duggan; Aaron Hart (Liam Marshall 83), Sam Cartwright, Nathan Stainfield, Dan Bucciero; Kyle Barker (Ben Greenacre 83), Archie Jones (Connor Peters 64); James Clifton (Toby Hilliard 64), Stefan Broccoli (Lewis Hilliard 64), Danny Draper (Josh Moreman 46); Elliot Sandy (Dylan Edge 46).
Boston (3-5-2): Rhys Davies; Tom Platt (Owen Sheriff 86), Jo Cummings (Lebrun Mbeka 63), Keenan Ferguson; Joe Starbuck, Tom Solanke (Scott Pollock 63), Zak Mills (Sam McLintock 46), Will Atkinson (Han Stevens 86), Harry Lewis; Jordan Burrow (Jordon Crawford 63), Claudio Ofosu. Sub (not used): Jake Lovelace (gk).
Referee: Alistair Wilson.
Attendance: 413.