For a RailFan, watching MPS skips are far more interesting than watching F1 race - Prince Maan

Basically guard was introduced on train by the British to protect(GUARD) the cash chest which used to carry the money from most of the station to a big junction. he used to ensure that money has been loaded in the chest and would signal to the driver to move on.Subsequently some other duties were added like looking after the freight load and wagons that used to be attached to the train. Seeing that the train moves after all the passengers have taken their seats, issue tickets where no staff is deployed and over all protector of train.
During MG era there used to be mixed trains where one or two wagons were attached to haul goods with passenger trains. In these cases...
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Assistant guard would do the duty of protecting the goods in the front portion of the train.Also trains which had many direction reversal assistant guard was handy.
Trains which i have personally seen Assistant guard.
7085/7086 Hyderabad-Bangalore express and Udyan express from bangalore