Across a sterile white table in a windowless room, I'm introduced to a woman in her forties. She has a square jaw and blonde hair that has been pulled back from her face with a baby-blue scrunchie. "The girls call me Marmalade," she says, inviting me to use her prison nickname. Early on a Wednesday morning, Marmalade is here, in a Finnish prison, to demonstrate a new type of prison labor. The table is bare except for a small plastic bottle of water and an HP laptop.

First, if you're a solver of the Mephisto series – which is unusual in giving the actual names of its setters – and have wondered what Paul McKenna does when he's not setting, you can now find out. The same setter is the Financial Times' Jason, and that paper interviews him as part of "an occasional series": Did your school mention crossword compiling in career discussions? It was never mentioned as a career option. I am a construction manager in the oil and gas pipeline industry. It is still a rare event for us to welcome a new compiler to the series.