66622, 20.45 Northampton Castle Yard-Tunstead Sidings (6Z99, 30L), Northampton station car park
Taken through the access gates to Northampton's virtual quarry better
known as Castle Yard the evening's empty wagons are seen being marshalled prior to departure by Freightliner's 66622. The 66 will work the 20.45 Northampton Castle Yard to Tunstead which carries a curious headcode of 6Z99; can anybody enlighten me as to why this is?