Lowell,
I don't know the history of these companies, probably DT can tell us something of it, but I can tell you that "hand forgings" were invented just for this type of low production manufacturing.

A "hand forging" is one that is done without a pre-contoured die to shape the part. The idea of getting the benefit of idealized grain flow is still a goal as with die forging.

"hand forgings" are still done today for short run jobs. Nearly all are done on powered hammer machines while the operator manipulates the red hot material with tongs and either operates the hammer with a foot pedal or another person operates the hammer machine. However, as the name implies, it was and probably still is done in some places, with a real hammer. I'm guessing if Purdey or the other biggies did their own forgings, they made hand forgings.