Very interesting report. However, I'm intrigued by the first photo showing how high the sea level was. As a teenager, (back in the mid 1970s!) my best pal and I went to Cleethorpes on a motorbike and camped out for a week, directly opposite this sand fort. We decided to try to get onto it. We walked, ran, waded a lot and swam a bit. We got onto the steps (which iirc had mainly been knocked out to prevent idiots like me gaining entry). We climbed up onto the deck but that was as far as we got because we had to leave before the tide turned. What I can't work out is if the sea level in general has risen over the last forty odd years or so, if it was an exceptionally low tide, or if I was a better swimmer than I remember. Either way, we must have been bonkers to do it. The currents as the tide runs out are very powerful because of the massive area of sand that has to drain away into the Humber estuary.