There wasn't meant to be a Part IV to this tutorial, but amendments need to be made to Part 2 - Drafting the block.
I couldn't understand how it was that the pinafore turned into Swampy so I thought I'd check my maths against Winifred's instructions because, well, maths were never my best subject at school. So, I got out the block, and my much-used copy of Winifred, and tried to work out where I had gone wrong. And there, in almost the first line, was the problem. "1/4 chest size plus 3cm". 3cm???? That's.... that's.... (time to count on fingers here) 12cm of ease! Genie Mac! A child wouldn't so much move comfortably in it, as move around inside it. So... I have redrafted the block, checked that it fits and have gone back to Part 2 and made liberal amendments.
I apologise hugely if you've been diligently following this tutorial over the last 4 months or so and have come up with your own Swampy (of course, you might have been smarter than I, and made proper alterations to the muslin!) You'll be pleased to hear that the original block doesn't have to be wasted - I am about to make a snowsuit type of thing from mine. I am hoping it'll fit nicely when made up in outerwear fabric, volume fleece and microfleece! It would also be a good block for a loose-fitting sweatshirt or hoody.