The M1 northbound between J6a and J8 has now been fully reopened after a load of vegetable oil was spilt on the carriageway last night.
Specialist cleaners were drafted in by the Highways Agency to clean up the carriageway and the motorway was fully reopened just before 10am today.
It is not known what caused the lorry to spill its load but no other vehicles were involved, the Highways Agency said.
A spokesman said: “It may well just have been how the load was stored or how the vehicle was being driven. Sometimes you do get incidents where vehicles do just lose their loads.”