Sir John Franklin’s wife, Jane, really did offer £10,000 to whoever found her husband and crew, last seen in 1845. But it was only in the 1980s that some graves in the ice were discovered and perfectly preserved bodies examined. Franklin himself has not been found. Only in 2014 was the wreck of HMS Erebus located, and in 2016 the wreck of HMS Terror. £10,000 in 1850 is £1,355,000 ($1,772,184 US) in today’s money.
This song was first recorded and popularised by A L Lloyd in the 1950s. I recorded a less-known version: https://songshepherd.com/2019/10/31/lady-franklins-lament/