On 03.09.17 13:34, Recliner wrote:
Alan Johnson on London's latest railway tourist attraction:

https://www.thetimes.co.uk/article/squeeze-in-and-the-london-postal-museum-mail-rail-will-deliver-you-to-a-lost-world-lvvzlmr3d?shareToken=6d140e276fa1eb76fc82d64640584 d9b

Obviously he got this bit wrong ("Back in the railway’s heyday,
battery-powered locomotives pulled cartloads of mail back and forth for 22
hours a day"), as the old mail trains weren't battery-operated.

This article seems to indicates that Mail Rail was a secret, at least at
one point in the past.

Was this actually the case?