The PO series is not listed in any UK post-war catalogue, which suggests that this series was treated by EMI as 'International', with records sometimes being shown in UK monthly supplements, and available to UK dealers from mid 1951 onwards to special order.
Thanks for the response, which confirms my concern that many dates given for the Parlophone Odeon P.O.-series records in this database right now are wrong.
This PO series was a 'Historic Recordings' re-issue series, first issued in Sept 1937 and reaching c.140 by Sept 1939. These discs seem to be recordings made ~1905-1910 (See here). Numbers c. PO 200 were being issued in the early 1950s (eg PO 198 - Dec 1952, PO 199 - Jan 1953), perhaps as a post-war revival of the series.
I've seen this record with a DTP tax code (valid 30 Dec. 1950 - 15 Apr. 1953) around the spindle hole and an NT tax sticker (16 Apr. 1953 - 28 Oct. 1955). Many of the other records in this series with a P.O.-prefix have, e.g., LT tax codes (13 Nov. 1947- 8 Apr. 1948) imprinted. The record was dated 1930; I think 1951 is more likely. I assume only the recordings are from the 1930s.