I am pretty sure the G6YC sound clip is on 160m - Top Band and would have been recorded in the late 60's. You can hear the typical 160m navigational beacon QRM and the transmit power levels mentioned were the power levels in force on 160m at the time. SSB was coming in then and replacing the 10 watt input power AM mode. It might have been recorded by Richard Castle who lived in the Gosport area of the UK near to Portsmouth. He posted a few messages here in the late 90's and I have some of his CCF recordings from the time.

Mark N1UK, G3ZZM