I found this image in the Australian War Memorial website with the description:
Fishguard, Wales. C. 1945-08. The strong “echo” from Fishguard and the surrounding area of Pembrokeshire coast as shown in a radar photograph.
Date range is WWII 1939-45.
I couldn’t see any other details of how it came to be on the AWM site, but perhaps someone else might know?
You can download the low res version (which I’ve attached here) free of charge from https://www.awm.gov.au/collection/C281804