I actually got those pictures from the gunsmith who took them and who "discovered" the rifle in Zambia and I wrote that short piece. The rifle had been used to shoot hippo by the local tribal chief (I have no idea how he came to own it) for meat and spent considerable time under water, probably to hide it from the authorities.
A sad end for a between-the-wars Rigby sidelock ejector .470! I have actually seen a WR droplock .425 that suffered a similar fate, although not quite as bad as the Rigby.
Thanks for providing that story. Which is going round.