Wouldn't be the yellow peril Network Rail HST▸ Measurement train that I saw in the yard at Exeter this morning would it?
I'm not sure that is a class 1 service.
The quickest passenger service is 2hr 4 mins.
Class 1.Express passenger train, nominated postal or parcels train, breakdown or overhead line equipment train going to clear the line or returning from there (Code 1Z99), traction unit going to assist a failed train (1Z99), or a snowplough going to clear the line (1Z99)