Correspondence in 1871 between Ordnance Survey officers reveals that while it might be considered desirable to publish the one-inch map of Ireland in full sheet format, it was impractical either to cancel the quarter sheets or to publish sheets in two different sizes. However, publication of this Drogheda large sheet, being ready, was permitted. The chief engraver examined and approved the printing of this copy on 26 April 1880.

Together with the similar large sheets of Ballymena & Coleraine and Belfast, this copy was donated to Trinity College Library Dublin in 2012, and we are grateful to the College for permission to reproduce it here. Trinity College also holds both versions of the rather better known Dublin sheet. No copy of Inishowen, the only other large sheet known to have been made, has so far been recorded: the copper plate is held in the National Archives of Ireland (OS 106/21).