Yup, at ScACC as well. SHT7W and so on. The numbers refered to the destination - 2 Heathrow-Glasgow, 3 Glagow-Heathrow, 4 Heathrow-Edinburgh and so on. The letter at the end was the specific flight of the day, not that they seemed to go in any particular order.
In the good old days, the Shuttle callsign prefix was simply the two letterd 'SH'. Shame there was never a Shuttle One as we would eventually have had a 'Shuttle One Tango'.
