Currently, this is the only service in RealTimeTrains from EUS calling at TAU that day, hopefully this is the relevant one!
Real-time train running information for 1Z73 0933 departure from London Euston to Penzance on 17/11/2024. From Realtime Trains, an independent source of train running info for Great Britain.
www.realtimetrains.co.uk
it runs from EUS to Willesden Jn, then briefly onto the North London Line towards Richmond. It leaves this at Acton Wells Jn and takes the Poplar lines (a chord joining onto the GWML).
The service does appear to call at Ealing Broadway and Reading but not for passenger use - it only appears in the detailed schedule
correction: this is a general GWR service and not the Night Riveria I think