This was supposed to be yesterday. I was sitting on the Cardiff/London train, supposedly about to write this very column, and realising something quite terrible. My head was entirely empty. A vast echoing void. Bigger on the inside, but with nothing in it. You could drop a pebble in my brain and wait for an hour to hear it land. No actually, you couldn't - that would be aggressive and unhelpful, so keep your damn pebbles to yourself.