(19 Sep 2023, 12:21 pm)V514DFT wrote I mean does the 18 need a DD to be on all day, likewise the same could be said for the 12, surely the short 12 and the 18 could interwork at Walker giving the so called 'required' DD for the schools, but the 12 did just fine for years with singles on it

While it doesn't need them on every working, the 18 is now Nexus-supported and the required capacity on said tender dictates the use of deckers all day.
Also, as has been stated, it is Slatyford that have the issue with singles on the 62/63 - whereas Walkergate run the 12 and 18. Walkergate haven't got any issues with their few remaining 62/63 boards - indeed, both of their boards are E400 allocated today.