Buzzybee: I apologise. I took prospero to mean that the 'Greek character' word was one of the 10. That was possible. I thought that first. But then I could find nowhere to put the 4-letter word in which a letter is repeated. So I looked for the initial 4-letter word elsewhere, and found it. You are perfectly correct when you say that one of the 'extra' letters is used in 21 ac. Hope we're still good!
sorry to create a wild goose chase - yes, I just meant that there were 2 possible solutions for 21, and the correct one depended on it being thematic in the accumulation of letters to make the theme word ...phew!
Always a pleasure, Brendan.
This grid is non standard, so Pasquale must have designed it to accommodate the number of 3 and 4 letter lights he needed but also those two 13s.
34 lights is at the very top end for Guardian grids.