I hadn't counted on this
13 little balls of wool to twist together across the back of the piece! And, what a nightmare it was when the whole lot fell off the sofa and became a tangled heap (I couldn't bring myself to take photos of that). However, a good tip from Eleanor helped in the end – I kept a spare pair of needles and moved each ball in order from one to the other as I worked. And, it all came out OK in the end.