Gunningham [‘Spin Hurwitz numbers and topological quantum field theory’, Geom. Topol.20(4) (2016), 1859–1907]constructed an extended topological quantum field theory (TQFT) to obtain aclosed formula for all spin Hurwitz numbers. In this note, we use a gluingtheorem for spin Hurwitz numbers to re-prove Gunningham’s formula. We alsodescribe a TQFT formalism naturally induced by the gluing theorem.