It's good to have a hobby, so they say, and mine is collecting hobbies. Over the years, I've tried stamp collecting (although after feverishly thumbing my Gibbons for several months, I decided that philately will get you nowhere), and I also spent a period collecting regal guano (which I retrieved from railway lines after the lavatory on the royal train had been flushed), and my recreational hours are currently devoted to banknotespotting, which is rather like trainspotting, only duller.