Mount Davis unknown building [????- ]

I'm interested to hear from anyone who knows what this was built for.

They are built from red brick, which makes me think they were built around the same time as the batteries on Mount Davis. As this is lower down the access road than any of the other buildings, perhaps it was the guard house?

The two ends of the building are still standing, but most of the sides have collapsed.

One end shows the remain of a fireplace and chimney.