(Note - this is fictional, and this crash obviously never happened in real life, thankfully. This is part of the WLTM novel though).
On the 28th November 2013, an unfortunate accident between a Crawley Luxury coach (KC04CLC), L1/Group TE6 (LN08MOM, formerly LN08MIM), a truck and a car happened outside Heathrow North Bus Garage on the M4. The coach and bus crashed into Heathrow North Garage itself, as a result of the accident throwing them down the embankment.
The death toll currently stands at 29, most coming from the coach, containing Year 10 students on their way to Windsor Castle on a geography trip. Also, three staff members, two at ADL and the TE6 driver, died. Two occupants from the car died, and 24 people from the coach died, including the driver, a teacher and 22 students.
The damage to Heathrow North Garage was that two ADL production bays for the E45H were ruined, and some other bays are damaged, limiting severely production of ADL products. Some structural damage to the building has been noted. ADL production is at a slower pace now, thus some staff and building is being temporarily moved to Falkirk whilst that plant's staff are on holiday. Repair work has already started on the damaged part of the garage. Three buses have been damaged (severely) - they are three new on production buses. They are what would be L1/Group TE1281, London OmniBus 653, and London United ADH171. A replacement "TE6" for London United is under construction already (diverted TE1283, a new bus will replace it).
TE6 as a fleetname will be reserved for the remembrance bus of the crash - a special bus built at Heathrow North Garage which will be named after all those who died at the crash. The name plate on the outside will say "in memory of the 29 who died at the Heathrow North accident, 28/11/13". This will be taken under care of the Heathrow North Garage team as a special bus. This will have a special number plate registration too.