Ah! I was misunderstanding! I thought the whole thing, wrapped in cloth was lowered into water, or laid on a steamer with the steam surrounding it. I missed the part about the pudding itself being protected from moisture. I do get the idea.
Rather like a Chinese steam bun? Moist but not wet.
I think I really like the sounds of this now! :D
Unfortunately, I'd have no idea where to obtain suet here. Do you suppose lard would make a good substitute as it too is an animal based fat? (It would impart a different flavor though).