I love your cable square Myrtle. It's fab. And the colour is gorgeous too.
You're right that it's still tight when using a cable needle but not as much as when you are using your ordinary needles because you can angle the cable slightly when you are knitting from it, which makes it easier.
I have a couple of cable needles that have ridges in them, indentations carved into the wood. They are really good at not having things slip off. I would offer to lend it to you pending the arrival of your new set* but it doesn't seem wise to be sharing addresses with people we meet on t'interweb, even in the lovely Blue Stocking.
*What type of set is the Walrus getting you? You've piqued my knitting nerdiness!