As embarrassed officials sought desperately to repair the damage, MacKay, a West Dunbarton psychologist, piped up: "I've got an interesting talk on the Glasgow tramway system."
Sighs of relief as a technician appeared. He fiddled a switch or two but produced a mysterious musical blast of Freddie Mercury giving it laldie to "Bohemian Rhapsody". As the technician retreated, Graham Donaldson, depute senior chief inspector, confessed: "The bulb has gone and we don't have another one."
The bulb apparently costs Pounds 200.