Having just binge watched the program again recently, Dad's Army has been on my mind and today I began a more in-depth look at what "Jerry" had planned -- possibly for the purpose of conducting a miniature wargame scenario set in Walmington-on-Sea.
I found a link to this fascinating film (14 minutes, no sound) of the barges and boats which the Germans would have used had Operation Sea Lion been attempted:
The transporter around the 12:50 mark certainly isn't hanging about - plenty of speed there. Of course, it could be speeded up footage. Either that or it's the warden effect when he jumped on a railcar and kept up with a speeding train!
Interesting footage, Doug, and yet more examples of German engineering.