I'm not a regular user of Highbury & Islington so I don't know
how long this has been going on. A (DC only) train drew in to
platform 1 at approximately 15:15 today. After the driver and a
few other people had changed ends it left.

Platform 1 is the most southbound. If was the westbound NLL
platform. As far as I can see it can only be used for
terminating trains from the ELLE. Hopefully, they'll be running
a service which the public can use before the official opening,
much as they did with Dalston Junction.
--
Roger