Hi John,they are a blast from the past - NCC Ollerton,was it the National Carbonising Company with a trade name of "Rexco"or summat like that and who was the main contractor for them,I’ve seen a photo somewhere which may have been yours of their fleet lined up in their yard.And Smiles for Miles,I remember them running out of the North-East coking plants,Derwenthaugh,Norwood and Monckton Jarrow spring to mind. 
I reckon that Atki of Smiles is ex Hanson,Wakefield going by the reg.
Great stuff 