I can't personally remember Mill Hill Railway Station, looking like this. Throughout my lifetime, I think there has always just been steps from the road, down to the platforms. Those 5 metal panels on the right are still there today and 3 of the ones on the left remain, but the rest have been replaced by walling.
Looking on an old map from 1933, that large mill in the background, stood on the corner of Mill Hill Street and Queen Victoria Street (kind of opposite where A.P. Taylor Glass are now) and was part of the Waterfall Mill complex. Waterfall Mills, as well as being on Peel Street, stretched quite a way down Queen Victoria Street.
(update) I have it on good authority from my brother Bill, that his mate Geoff, remembers the station looking like this in the late 1950's or early 60's. In fact he thinks he remembers the kid stood in the centre;-)
COURTESY OF THE CP COLLECTION