In 2003, my wife Patricia and I participated in a BBC TV documentary after something large and mysterious appeared in the sea near Pembroke Dock in Wales. We interviewed several reliable eyewitnesses, and then went looking for the beast with skipper Alun Lewis aboard his Cleddau King – an ideal boat for the job, equipped with the latest electronic gear. But whatever had been seen in the dock had fled before we got there.A search was undertaken using a fishing vessel equipped with high tech radar and sonar capability but no trace of the monster was found.
Fanthorpe raises an intriguing point given the naval activity in the area it could be some kind of bizarre secret sub.
Full details in his book Unsolved Mysteries of the Sea By Lionel Fanthorpe, Patricia Fanthorpe (2004) 47-51. Apparently Richard Freeman the CFZ's zoologist and monster hunter extraordinary also went to look for the beast as well. I am waiting to get more details from him. This makes the case all the more interesting!