I see where you come from, but the sidings are at a higher level, as are the two cabins seen 'above' (in the image) the stabled rolling stock. To the right of the buffers there is a retaining wall, the shadow from which can be seen in the access road it protected, coming from York Road. The image can be deceptive if one is unfamiliar with the ground level detail etc.
Also working at Waterloo for many years I was able to take the attached (amongst others) from the station roof during the rebuilding for the then new International station, and is one of my collection that I have since donated to the South Western Circle (
https://lswr.org) for their archive. It clearly shows the ground level of the North Sidings as was, including the lift shaft of the old W&C Anderson lift, but crucially also shows the retaining wall and the lower level access road that went out (right) to York Road.
Apologies for veering slightly OT here btw!