I have a feeling the figure for Exton might not be correct here, the reason being that I've just been let off 2T20 with the unusual combination of 158769 & 150265, and I was forced to alight using a local door, which wasn't necessary at either of the Lympstone stations. The reason seemed to be that the rear cab door of the 150 was off the end of the platform at the rear of the train, and due to the fact that this unlocks when the doors are released, I suspect for safety reasons a full door release wasn't permitted. Must admit I find it a bit strange that a 158/150 combo is being used when 150221 is out running as a single unit, but oh well!
For those interested, today's Avocet turbo diagram is in the hands of blue 166211.