Our College archivist, David Kay, has come across this clip on YouTube which was recorded in the College Chapel at the end of the summer term in July 1937: https://www.youtube.com/watch?v=zMQz7zLermE&t=985s. It is part of a radio broadcast by the BBC in a series called Vespers. It was later available in a set of four 78rpm records, hence all the crackling.
 
The clip has been set to start at the point when the assembled school sings two choruses of O Beate mi Edmunde. Rather than the rousing anthem that we are familiar with today, this rendition is slower paced. 
 
Enjoy the listen!