Chessical: This is the only drawn game of the match, and it is decided by errors.
Mackenzie equalizes out of the opening, but then with <19...Bxd5?!> gives MacDonnell attacking prospects on the King-side with <f5>.
MacDonnell could have secured a very substantial advantage by <22. f5!> exf5 23. e6! Bc5+ (not 23... Qxe6?? 24.
Qxg7 mate) 24. Kh1 Qe7 25. Bxd5 cxd5 26. Rxd5.
Instead, he loses the thread of the position and with <27. Rc1?> allows Mackenzie control of the <c> file (27. g4 to force f5 looks best).
Mackenzie uses this to build up pressure on the <f4> pawn, and is presented with the opportunity to win immediately when MacDonnell leaves his <Rf1> unprotected <31... Qxe5!!> 32. fxe5?? Rxf1 mate
<33. Rff3??> should have lost the exchange and the game, but Mackenzie's <34....Rxd2??> blunders the game back to a draw. He obviously missed MacDonnell's next move (moving his attacked Rook) and instead only saw <35.Rxd2??> with Qb1 and mate to follow.