On 2017\09\03 17:33, Guy Gorton wrote:

"Mail Rail is opening to the public for the first time" is not quite
true either. I was one of many people who visited it some years
although we could not ride the trains. Was it soon after it ceased to
be used for the mail? Can't remember.

It's normal to say a railway becomes "open to the public" not when the
public can look at the trains but when they can ride on them. The
Barking Riverside extension will certainly not be described as "open to
the public" during the shadow running period, when the trains will be
visible for all to see.