It looks to me that 6V74 might be a continuation of 6V73 which left Cliffe Vale sidings in Stoke on Trent at 1517h this afternoon and is due at Exeter Riverside NY at 2320h.
Real-time train running information for 6V73 1507 departure from Cliffe Vale Jn to Exeter Riverside N.Y. on 16/08/2024. From Realtime Trains, an independent source of train running info for Great Britain.
www.realtimetrains.co.uk
The sidings in Stoke are labelled "Cliffe Vale China Clay siding" on openrailwaymap.co.uk
So it looks like returning china clay waggons back to St Austell
EDIT: And possibly going on to Goonbarrow sidings next to the quarries as 6G03 tomorrow, or to Parkandillack as 6P23 on Monday.
Train information at St Blazey Ss all day on 17/08/2024. From Realtime Trains, an independent source of train running info for Great Britain.
www.realtimetrains.co.uk