Passengers would then transfer to the Great Indian Peninsular Railway's Calcutta Mail at Manmad to proceed to the northern and the eastern parts of the country.

The East Coast line between Madras and Calcutta opened in 1900, providing a shorter route for the passengers bound to Calcutta, but the passengers bound to Delhi, Lahore and other major cities in the north, continued to rely on the Madras–Manmad mail service.

A record in through-train running was set in 1921 by a military train conveying families of a regiment from Peshawar to Cannanore (now Kannur in Kerala).

[2] Following this record journey, interest in a shorter through route between Madras and Delhi was rekindled and the Nizam's Guaranteed State Railway hastened the construction of the missing rail link between Kazipet and Balharshah Junction.

[4] Shortly after the inauguration of the service, from 15 October 1929, the two through carriages operating between Mangalore and Peshawar were restricted to run between Mettupalayam and Delhi with Slip Coach to Peshawar/Landi Kotal .

Until the mid-1960s, the Grand Trunk Express completed the 1356 mile journey between Madras and New Delhi in about 50 hours.

Today, the train covers the 2182.4 kilometer journey in 35 hours and 15 minutes, with 40 halts (exclusive of the terminals) at an average speed of 62kmph.

[citation needed] As per the numbering of the Indian Railways, the train has been assigned the numbers 12615/12616, with 12615 being assigned for the Madras Egmore (MS) – New Delhi (NDLS) run and 12616 for the New Delhi (NDLS) – Madras Egmore (MS) run.

The important halts of Grand Trunk Express are :- It is hauled by a Royapuram based WAP-7 locomotive on its entire journey.