Evidence that public transport announcements of "please make sure you take all your belongings with you when you leave the train" have very little impact on an evening commuter's brain is that one hapless Robert Napier left his violin on a train from London to Taunton, 2 and a half months ago. No cheap fiddle, this. No. He'd just been to get it valued. It's a violin worth around £180,000 and a 17th century......