One move from becoming World Champion

One game, one move. Often this is the difference between becoming World Champion and just being 'unlucky'. Not only does it happen under the pressure of over the board chess, but it also happens in the world of CC.
When CJS Purdy became the first CC World Champion, he acknowledged that his game against Napolitano was the key game of the event. Reverse the result of the game, and Napolitano would have taken the title.
Keith Foster alerted to me to this fact while sending me a suggestion for a future article in Australian Correspondence Chess Quarterly. He pointed out the the decisive mistakes (for both sides) occurred around move 31, with both players missing decisive continuations. Some further research revealed that this had been noticed around 1998 in an article in Chess Mail, although it was Fritz 5 which made the discovery.
Here is the game, without notes, which you can dissect at your leisure.


Purdy,Cecil John Seddon - Napolitano,Mario (ITA) [E26]
1st CC World Ch Final 5053 corr ICCF, 1950

1.c4 Nf6 2.d4 e6 3.Nc3 Bb4 4.a3 Bxc3+ 5.bxc3 c5 6.e3 Nc6 7.Bd3 e5 8.Ne2 d6 9.e4 Nh5 10.0-0 g5 11.Bc2 Nf4 12.Ba4 Bd7 13.Ng3 cxd4 14.Bxc6 bxc6 15.cxd4 Qf6 16.Be3 h5 17.dxe5 dxe5 18.Rb1 Rd8 19.Qc2 h4 20.Nf5 Bxf5 21.exf5 0-0 22.Rfd1 Nh5 23.Bxa7 Ng7 24.a4 Nxf5 25.a5 h3 26.a6 Ra8 27.Bc5 Rfe8 28.a7 e4 29.Rb7 Nh4 30.Qb3 Qf5(D) 
31.Rdd7 Nf3+ 32.gxf3 exf3 33.Kf1 Qxc5 34.Qc3 Rf8 35.Qd3 Qe5 36.Qxf3 Rae8 37.Rb1 Qxh2 38.Rb3 Qe5 39.Qxh3 Qf4 40.c5 Qc4+ 41.Kg2 Re4 42.Qf5 Qxb3 43.Qxe4 Kg7 44.Qf5 g4 45.Qxg4+ 1-0