Hi Evelina,
I was relating your story to my neighbour who happened to holiday at Downhill when he was young. He has had a look and is "95% sure" its Downhill with the Bishops Road behind. There was a local hotel at his time built of the same grey granite stone. He was not sure if they were Railway cottages for workers or part of the local landed estate. The Bishops Road is named after the Lord Bishop of Derry ie the Earl of Bristol ie connected to "Bristol Cream" Sherry. His estate including Downhill was taken over by the National Trust . I have pasted some bits below including a web page on Downhill. There is plenty on Google.
Downhill: Downhill in county Londonderry was built from the 1770s onwards by Frederick Augustus Hervey, 4th Earl of Bristol and Bishop of Derry. The estate is on a cliff overlooking the Atlantic Ocean. It was inherited in 1907 by Sir Hervey Juckes Lloyd Bruce, 4th Baronet (1843-1919), who had succeeded to his second cousin's estate at Clifton in 1896. In 1919 Downhill passed to his eldest twin son, Sir Hervey Ronald Bruce, 5th Baronet, while the Clifton lands passed to the younger twin, Percy Robert Bruce, who assumed the surname Clifton.
Downhill was tenanted by members of the Hervey Bruce family until 1950, but is now owned by the National Trust. The mansion is in ruins, but the Mussendon Temple overlooking the sea is open to the public.
Website covering Downhill
http://www.northcoastni.com/explore/castlerock-and-downhill/I mentioned before that I was up in the area recently and that was in connection with my cousins relatives who lived in Castlerock -nearby- when they were young. I have sent off the photo to them and will let you know what they say in due course. They would know the Downhill area.
Hope this helps, as I explained I have a note of your connections set aside to bring with me on my next GRO outing.
Regards
Peter