And so it comes to be that the song that purports to be Scotland's national anthem cannot actually be played on Scotland's national instrument. Not that Scotland's pipe bands have allowed such a minor consideration to inconvenience their efforts, as they have caterwauled on regardless on the expanses of Murrayfield and Hampden Park, skirling their way through the tune to the point - the ''think'' of ''tae think again'' - where it all goes cullen skink.