So I cut up (another!) old cot sheet (the other’s are going in the Learner’s quilt but the one I used for this one was thankfully 100% cotton so that made it much easier to use).
The final quilt is 25″ x 33″ – sort of the bottom width might be a bit closer to 24″ due to some reluctance on my part to cut off a section at the bottom during my squaring up process!