I downloaded the Geneva Mystery audio from Amazon.com because it was only $11 or $12 (some of the others are available, but they cost more money than I want to pay - but I don't think BBC Radio 7 ever aired this serial - only 6 eps instead of 8.)
It's not very good - and its different from other Temple mysteries in that in the first couple of eps, scenes took place between two characters - not with Paul and his wife present. The word "bitch" is actually used to describe a character, and Simon Lack's Vince Langham calls a character a "basket" twice (obviously a version of bastard.)
In addition, Margorie Westbury must have had a cold, because in the later episodes she sounds like she has laryngitis.
Simon Lack is in this as film director Vince Langham. He does not have a very large role, though, but he does well with what he's given. In this one he gets beaten up (there's always at least one character beaten severely inevery Temple serial - usually they die. Vince survived, though.)
This is the second to last Paul Temple serial, recorded in 1965. The next, and final Paul Temple, Paul Temple and the Alex Affair, was not recorded until 1968. That's the one that gave Simon Lack his best role in the series, as the hallucinating Carl Lathom.