I've looked through the ModKeys section of the TextBlade app - all modifiers were there, except for the "Esc" key.
As I'm doing a lot of sysadmin work I need the "Esc" key, at least for something like "vi".
So - where's the Esc key?
When I look in the Textblade app it is at the top-left on the Green layer (at least for the UK QWERTY keyboard).
Found it, thanks. Maybe it was too tiny for me to see.
Geeky technical nit-pick: ESC actually isn't a modifier per se, it's a for-real character all by itself.