Had a quick search on Portkil and Rosneath in here and nothing come up, so this may be of interest.
Check the War & Defence section at http://www.coveandkilcreggan.com/histor ... enulevel=8
Although nothing remains of the Rosneath naval base pictured, a small unsigned single track road to the left, a few hundred yards before the Kilcreggan ferry pier leads to the hamlet of Portkil (it's the residents only access, so be kind and walk the last part or you'll have to park in their gardens )
At the end you will be rewarded by the gun mounts for the Portkil battery, integrated into the houses that are there now. Below these is e deep trench with recessed doors leading under the battery. On the approach to the battery, I recall there may have been a store or larger entrance, but the weather was traditional Scottish and detailed vision was beginning to suffer, and it seemed to keep the local well bolted indoors too.
Sorry I can't post any pics at the moment as this was a whle ago and I have prints only and no scanning capabilities up at the moment, but seems a shame not to let anyone know that's maybe interested.