Philip Marlowe via Australia.

A radio series in Australia, Philip Marlowe Investigates, was broadcast in 1953 starring Australian actor-writer-producer Reginald Goldsworthy as Marlowe. Episode 1 was "The Lady in the Lake," and episode 2 was "The High Window." Below is "The Lady in the Lake." The American accents are fairly proficient.

NFSA · Philip Marlowe, Eps 1 The lady in the Lake (1953)