Sir I couldn't find the reference now, but as I remember there were 2 trains for transport from Howrah to Delhi, one was a slow connection which he complained and the other was the Howrah-Delhi-Kalka mail. Though the author mentions existing train, he didn't write if the train was extended upto Kalka from Delhi. It is more likely that it was another train that ran to Delhi that journeyed from mid- late 1866/early 1867.