Over 125 years ago, barely a year and a half after the Tay Railway Bridge was built, William McGonnagal composed his poem about the Tay Bridge Disaster, the poem about Britain's worst-ever civil engineering disaster. Over 80 people lost their lives in the fall of the Tay Bridge, but how did it happen? The accident reports say that high wind and poor construction were to blame, but Peter Lewis, an Open University engineering professor, tells the real story of how the bridge so spectacularly collapsed in December 1879.