These two solid observation posts were exposed by building works in 2013 and photographed at that time. There exact use has not been confirmed, but they appear to be from WW2. The are two separate positions, with a large pedestal at the front. These would appear to be for range finding/observation. There are adjacent crew shelters.
Another contributor has suggested that these were in fact gun positions for two 6-pdr Anti-Tank guns which could protect the entrance to the tunnel behind and provide enfilade fire on any vehicles moving up the road. This seems the most likely.