Thanks Robbie. What you said about the string in 4507 confirms what Tonguello said. I would still like to allocate a part number to the string, so colour, length and thickness would be helpful.
I think you are right about the 4554 Ninja too (and again, Tonguello agreed) having two pegs. I noticed the one in 5849 had only one 'peg' on the belt/sash and wondered if some versions of 4554 also had the single-peg belt (its impossible to tell from the box pics, though some pictures on Google show no front peg, these may be from 5849 too).