Rounds: Here.
This is Simon's sixth night, and his last until the finals regardless of the result. Richard asks about highlights, and Simon understandably mentions his must-get conundrum solution in episode 436. He was very nervous, shaking hand, etc.
The last obstacle between Simon and becoming a retiring champion is Andrea Boyd, a control systems engineer. Andrea commutes to work every week by plane, to what she describes as a very remote site in the middle of South Australia -- the Olympic Dam mining centre. She has a work house there that she uses throughout the week. Andrea is part of the team that handles the automation for the entire site, both underground and above ground. It sounds like quite the task!
It was another close game, and got off to a good start with both contestants finding the only eight-letter word in the first round. That was followed by a pair of invalid entries, as Andrea miscounted (or misdeclared) the length of her word, and Simon tried for a risky nine that did not come off -- the perils of the Scrabble-players lexicon! Andrea pulled ahead in the numbers round, only for Simon to get most of that ground back in the next round with a risky but valid eight. The next numbers round saw him manage to get closer than Andrea and gain the lead, but with the remaining rounds not providing any swing it was either player's game to win at the conundrum. Simon solved it at the nine second mark to win the game 55 to 40, and successfully retired.
I had to risk a couple of words, but they both came off. I knew I was short of best on one round, but it still took me a while after time to spot the better option. I solved the conundrum quickly, and in the end there was just that one round between me and optimal. Another good day for me!
Update: Thanks to Victor for pointing out a better word in round seven in the comments. So I was two rounds off optimal, which is better in some ways.