Late last night, I finished it. Said "scene" had taken 18,000 words. At the heart of it, was remained what I'd envisaged: a confrontation in words between two men. Hangers-on and minions got involved along the way, and added their commentary, but, still... 18,000 words! In what was originally envisaged as one two-player scene! It was all written in 3 evenings, with me being at work all 3 days.
I feel quite drained today, but very achievementy. It's years since I've written so much so fast. But... phew! *shakes head in wonder.* How these stories grow!