I found the corkscrew! I cunningly placed it on top of my box of wine. Where I had already looked, but obviously not very well as it was just pushed to the back a bit (under a shelf, so not very visible).

Having used the first bottle of wine in the beef stew I have opened another bottle to drink, and have been able to use the un-screwed cork that I had to push into the bottle as a seal for the newly opened one, which means I have been able to use the wine stopper in the bottle of soy sauce that for some reason had a non re-sealable bottle top and has been sitting with a bit of foil squished onto it as its lid.