Lovely!
That is exactly as I would want a Royal.
I suppose it could be possible that H&H had kept this gun for another client whom never took delivery and then eventually resold it to Mr. Owen.
I don't think that the option of getting bolsters would have kept this from selling for 20yrs and you just never know what makers did for clients at the time.
I was shocked to learn that my Westley Richards that was made for the Maharajah of Alwar in 1926 was actually built on an earlier action and renumbered. I should get the ledger page on that gun to see if it was one of his own guns returned for the build. Can't imagine that though as armory space and money were of no concern to him!