This is such a cute knit, like so many Debbie Bliss patterns.
I adapted it only slightly – I don’t like neck seams so I joined both shoulders and knitted the neck in the round. I was panicking quietly as I approached the end because I was down to a couple of metres of the main colour yarn, but I had just enough left to sew it up. The pattern is indeed correct – three balls of the main colour yarn are enough. Just!
And I’m also now a complete convert to mattress stitch. I hadn’t realised previously when I’d tried it that you need a garter stitch edging to make a neat mattress-stitch join. Last time I did it the seam was horrible so I’ve stuck to oversewing, but I read an article about it recently and thought I’d give it another go with a garter stitch selvedge. Very nice indeed!
If I didn’t know where it was I wouldn’t be able to spot it, I don’t think. So thank you to Grumperina for her fantastic tutorial! I can’t find it on her blog now or I’d link to it.