National Coal Board v Gamble  1 QB 11
Aiding and abetting and necessary mens rea
M, who worked for a haulier firm, had his lorry filled up at a National Coal Board (NCB) colliery. He then drove to a weighbridge where the operator told him that his load was overweight. M, nevertheless, accepted the risk of taking the overload. He was later stopped by the police. His firm was subsequently convicted of violating the Motor Vehicles (Construction and Use) Regulations 1955. The load was to be taken to a power station of an electricity authority to whom the NCB had to supply coal – so the NCB was charged with aiding and abetting the firm. The NCB appealed.
The NCB argued that as the contract did not include a ban on overweight lorries, it was not required to make sure that M’s lorry carried no excess weight. Further, M was not the NCB’s servant so it had no right to detain him. Had the property not passed, the NCB could have stopped the lorry from leaving the premises. The issue was whether the NCB should have done so in order to prevent being held to have aided and abetting. The NCB claimed that its mere knowledge in this illegal prize fight, without any coincidence of purpose with the perpetrators (the firm) and without any sign of approval of the perpetrator’s actions, did not make it an aider and abetter.
The Court found that aiding and abetting was proved if there was a positive act of voluntary assistance and knowledge of the circumstances constituting the offence. Motive is irrelevant in this case. Applying Ackroyds Air Travel Ltd. v DPP  1 All ER 933, the Court held that the property only passed to the buyer when it was weighed and the weighbridge ticket was handed to M. The sale was thus completed by the weighbridge operator despite having had knowledge that an offence was being committed. Thus, the NCB’s actions constituted aiding and abetting.
P.S. Slade J, dissenting, agreed with the NCB’s reasoning.