Nice captures! The Circular railway has always been one of the most intriguing section of Calcutta rail network to me, with a considerable history (more than 120 years worth of it) as the Calcutta Port Commissioner's railway.
Majerhat, from where the circular railway branches off, has an interesting history. It was originally called Kalighat (The terminus of the Kalighat-Falta narrow gauge light railway which was operational until about 1957). Later, the name was changed to Majerhat, and a new station (present day New Alipore) was named as Kalighat instead. Now, I believe, the Calcutta Metro has a station named Kalighat. So, this station probably holds the record for being 'moved around' the most number of times!
Kalighat happens to be a place in South Calcutta famous for it's Kali temple.
The metro station has been named after it's namesake place, something that is not usually found in Kolkata Metro.
However I am definitely curious as to why New Alipore station would be named as Kalighat!
It was probably named so as it was the closest railway station to the temple. When the old Kalighat station was renamed to Majherhat (It was written as 'Majher Aat' at that time), the new station, which was closer to the temple was just named 'Kalighat'.
Restoration of KFR via Budge Budge Proposal