UPDATE 5 July 2018

Decided to add length so picked up stitches at lower edge of body and pulled back all the ribbing. Added another 6cms and made a split garter stitch lower edge rather than 1x1 ribbing. New pic to be added after reblocking.

20 March
Hibernating while waiting for a 3mm needle to arrive.
28 March
Resumed knitting. Needle arrived yesterday but I’ve been ill.

I used this knitting calculator to help me with placing the waistband increases correctly.

Standard BO on waistband and neckband.
Neckband only BO with 3.25mm needle.
BO in pattern on wrists.

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Notes in case I make this again:
Make the body several cm’s longer before waistband.
Medium is a good size above the waist but I could do with a few extra stitches (over those in the pattern) for the waistband to fit comfortably on the hips.
Neckband should be BO in pattern. TBC once blocked and dry it might look better.