Started to fix our creaky stairs. Whilst laid up in hospital, I mentioned it to my fellow room mate about the stairs creaking. As a builder, he recommended a wood adhesive that expands slightly, and sets in either 5 mins or 30 depending upon which one you buy. He even said where to buy it.
Today I fixed 5 of the bottom squeaky steps with it, and just have the top 4 to sort tomorrow. Brilliant stuff. Everbuild Lumberjack Wood Adhesive. Remove carpet, apply glue along the joints and gaps, let set, no squeak. On the bigger corner stairs I used an L bracket to strengthen the joint between the steps.
One happy wife ! She's been mithering me for ages to fix it, but I hadn't found away to stop the squeak, even with additional screws.