This is Kate Davies' Toatie Hottie, a hot water bottle with a knitted cosy for protection. I got it as a kit a while ago, and the J&S Heritage yarn that comes with the kit is a real treat to knit with, it's super soft. Luckily, the hot water bottle itself was included in the kit as well, so this comfort knit can be turned into an item of comfort as soon as the last stitch is cast off.
Though it feels weird not knitting on a big project now (Hermoine cardigan is finished, yay!), I'm quite satisfied for the moment.