Horsham 1's final match & a puzzle

A glance at the website revealed I hadn't posted a report for the final match of the season vs Worthing 2 which confirmed Horsham 1 in second place in Div 1. So here is the scorecard and a puzzle...

G.R. Lock 0-1 D. Miller
M.C. Forster 1-0 P. Larwood
J.C. Mansson 1/2-1/2 N.H. Skinner
A.R.J. Higgs 1-0 G. Neale
D.N. Roberts 1-0 D. Wallis

3.5-1.5 to Horsham

The position is Higgs-Neale after 20...exd4 and it looks like Black has some compensation for the knight in the form of a pawn, open lines and White's exposed king. However White has a knockout blow seen in advance - can you spot the classical theme? Answer is below in the comments.