Slippery When Wet

My family and I moved house recently. It was a gradual move, i.e. we got the keys to the new flat on a Monday and finished moving the following Sunday. This meant we filled and emptied our little Toyota Yaris (Car Of The Year in 2000, no less!) around twenty times that week to move the contents of cupboards, drawers, shelves, etc. to the new flat. I thought that would be a less stressful way to move house. And it was... to some extent. The stressful part was going down metal stairs outside our old flat, at night (when the kids were asleep), carrying two or three Ikea bags full of clothes, pots and a random set of Tintin DVDs I bought in 2012. However, I never slipped once during the whole move, no matter what I was carrying. By the grace of God! I have slipped on those stairs before, though. Twice, in fact. The first time was on a bright, sunny day, on my way to work, laptop bag on my back. The second was on a cold and wet day, on my way to work, laptop bag on my back. Rememberi...