A van has been seized after police officers pulled the driver over on the M4.
Police described the van as "meandering" along the stretch of the motorway when their computer system flagged the vehicle for having no insurance.
Upon stopping the driver, officers issued a roadside drug wipe after smelling substances in the vehicle.
This came back positive for both cocaine and cannabis and the driver was arrested.
Officers found drugs in the van and referred one of the passengers to druglink to raise awareness of cannabis use.
A Thames Valley Police spokesperson added: "No such leniency for drivers - he's currently giving blood for forensic testing.
"It's a long wait for the test results, but it's an even longer walk back to Swindon."
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