The line to Manchester was closed for engineering works yesterday, resulting in the Liverpool to Manchester Airport service being diverted to Wigan North Western, thus giving the west curve at Parkside a rare regular service.
Normally, this route has just one passenger train one way on weekdays, the 06:44 Wigan North Western to Liverpool Lime Street.
At Wigan, the service was reversing in platform 1, not normally used by class 319 units.
I'm not sure why the trains didn't reverse at Earlestown as they did on Saturday.
(Correction: The service terminated at Earlestown on Saturday, but the trains ran on to Parkside Junction to reverse.)
Update: For anyone who wants to try out this unusual route, similar operations are scheduled for the first three Sundays in 2016.