Thanks Mike.
At Reading the ticket halls are at ground level by the north and south station entrances. Only the lower numbered platforms (southern side) are accessible without using the overbridge (and only from the south entrance). Elizabeth Line uses northern platforms (13/14) so in the example above the four escalator journeys are up to the overbridge, down to the northern ticket barriers, back up to the overbridge and back down to the original platform 14/15 (which is adjacent to but not accessible from the north entrance).
If the Gatwick train departs from Platform 5 then yes it’s only 1 up 1 down.
And it appears it’s not GWR’s station, it’s Network Rail’s.