Oldest trains still running
Trains keep getting their schedules changed, their routes changed, and their names changed over time, so the answers to these questions are a bit fluid. The Bangalore Mail has been running in various guises since 1864 (1862?). The Deccan Queen and the Howrah-Madras Mail have been in operation since the 1930s. So has the Howrah-Kalka Mail. The Punjab Mail, the Frontier Mail, and the Grand Trunk Express are other trains that have been running for a long time, however, their names have changed and/or their routes / termini have changed too. The 2 Up / 1 Dn Mail between Calcutta and Delhi, started in 1866, is the direct forebear of today's Howrah-Kalka Mail. The Poona Mail (Bombay-Poona) introduced...
more... in the 1860s was discontinued in the 1970s. The Flying Ranee started under that name in 1950, but it had its predecessors (Flying Queen, Weekend Special) in 1937 and 1906.