Lyric discussion by cesium14 

Cover art for The Deverell Twins lyrics by Black Box Recorder

In St Bartholomew's Churchyard at Lower Basildon, there is a joint tomb for two sons of Edward and Priscilla Deverell. Both boys drowned together bathing in Thames. The tombstone reads "They were lovely and pleasant in their lives, and in their death they were not divided."

Probably where the names come from in this song.