The joy of irregular calling patterns ... where such things happen, it's usually on a line / with a driver who doesn't normally stop at a particular station; they're still following signals so there's no safety concern.  The "Berks and Hants" seems to have just about the most erratic call pattern in GWR^▸ (Great Western Railway) territory, so statistically it's more likely to happen there than elsewhere.   It's also been known to happen at Chippenham; drivers based in Wales are familiar with using the line via Chippenham and Bath Spa when the line via Hullavington is closed, but on those diverted services they don't stop.   When they find themselves driving the 05:18 Paddington to Swansea ...They wouldn't work the 0518 from Paddington though because they wouldn't begoing to London to return at that time