This was the flag of the HMS Dublin
The Battle of Jutland was one of the key naval engagements of the First World War. HMS Dublin played a part in the battle, which was fought in 1916. The ship had been adopted by a committee of Dublin citizens and businessmen who raised funds to provide it with a band and other amenities.
When the ship was decommissioned in 1926, Dublin Chamber of Commerce was presented with its battle-scarred ensign – complete with Union Jack – and in turn the Chamber donated it to Christ Church, since when it has languished, unseen, in the cathedral crypt.
With thanks to Christ Church Cathedral
Watch the first part of a Battle of Jutland documentary: