कोशी की जीवन रेखा — मानसी सहरसा रेलखंड - Prabhat Sharan

Attached scan of the Railway board report from 1929 mentioning the introduction of this train.
Prior to this, a 'Mettupalayam mail' operated between Madras Central and Mettupalayam between 1908 and 1929. The Blue Mountain express was started as a special daily train with only First and Second class accommodation and limited third class accommodation between Madras and Mettupalayam. A connecting meter gauge train between Mettupalayam and Ooty was operated with the same name, in connection with the BG train. The MG Blue Mountain express was discontinued in the 70's, replaced by a passenger service, but still operating in connection with the BG portion.
...
more...

On the BG, First and Second class passengers were not allowed to book tickets to destinations between MAS-Erode. While only third class passengers booking till Mettupalayam were allowed on-board. On the MG portion, the third class was mainly for the servants of the passengers on the first class, with limited accommodation for others.
It was a fast, luxury train when introduced. The schedule was as follows -
BG: MAS - 9:15PM, MTP - 8:35AM; MG: MTP - 9:20AM, Ooty - 12:36PM.
In the return,
MG: Ooty - 2:20PM, MTP - 5:15PM; BG: MTP - 6:10PM, MAS - 6:35AM.