321425 arrives at Hemel Hempstead with the 12:49 Northampton to Euston Network SouthEast service on 2 September 1990. Then only a few months old, the 321s were introduced on these outer suburban services to replace the older Class 310 & 317 units. The P suffix to the number at this end of the unit indicates that this DTSO vehicle contains a small parcels area that can be locked off by an internal sliding door. The DTCO vehicle at the other end of the unit does not have this feature.