Damascus, Let me make an alternative suggestion that your TP is actually a JP, which is stamped on my hammer Boss in a similar location and on the action itself. According to Dallas, Boss sourced barrels and even entire actions from John Portluck, a supplier to the trade. It is possible that Purdey sourced these barrels from Portluck. Part of the fun of these old guns is that we may never know all of the answers!

Owen