390 001 working 1B74 17:30 Birmingham New Street to London Euston, stood one signal north of Kings Langley for 70 minutes on the up fast with defective brakes on coach E. Services diverted from the fast to the slow at Bourne End, and back to the fast at Watford.
A rotational test was carried out at 19:09 and the driver was unable to release the brakes. The down slow was then blocked to allow the driver to manually isolate the parking brakes on that side of the train, and then the same on the down fast, diverting services onto the alternative lines.
At 19:52 the unit moved forward to Watford Junction where the train was terminated 82 minutes late. The unit then went forward to Euston (driver only and passengerless) as 5B74, and then on to Wembley depot.
At 20:16 1A16 17:37 Lancaster to London Euston called additionally at Watford Junction to collect the detrained passengers. Normal working was then resumed.