This Pickett-Hamilton Fort has recently been erected at the museum.  It is complete with the firing step and is only missing the internal jack to raise the top section.  They were installed at air fields in the early part of WW2, in threes, one of which would have been in the runway.  When lowered the top was flush with the ground.  We have erected our example 75% above ground so that it can be seen.  They would have been manned only when the airfield was under imminent threat.  Access is through a hatch on the top.