Straight from the Birmingham Proof House, which is the most reliable source I know of when it comes to questions about proof, service pressure etc on British guns:
"The equivalent transducer values that should be used for comparison with SAAMI transducer values are 740 bar service and 960 bar proof, i.e. 10,730 psi (service) and 13,920 psi (proof)."
This was in responce to my post stating the "Older" 3 ton service pressure had been shown by "Simultaneous" crusher & tranducer readings to give an "Actual" reading of about 8960psi.
""IF"" the actual pressures used have not changed then I read that as saying those old pressures were in fact 10,730 "Actual" psi's. Peresonally I need a litle more proof to show they were. I did state verbatin where my figures relating 3 ton to 8960psi derived from. You strongly implied they were all wrong & you had the final word from the Birmingham Proof House. However everything you quoted was for post 80's "Metric" figures. I do not believe these to be totally applicable to the earlier proofs, but could possibly be proved wrong. If so then 10,730 it is.
