The government of the day went a bit further than having them cross picket lines!!
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"The London docks were besieged by striking dockers and middle-class blacklegs were afraid to go there. The docks were heavily guarded by soldiers in full war-kit and machine guns were mounted everywhere. The Home Secretary met high army and naval officers,
"Make your own plans" he said. "Use whatever force you require - I give you carte blanche - but my orders are that the London Docks must be opened at all costs."
Warships took loads of blacklegs down the Thames at night and one hundred food lorries were loaded. Next morning the lorries passed through the East End in convoy guarded by hundreds of police, two battalions of infantry with fixed bayonets, a number of tanks and ten armoured cars.
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On the 7th of May the government issued the following proclamation:
"All ranks of the Armed Forces of the Crown are hereby notified that any action which they may find it necessary to take in an honest endeavour to aid the Civil Power will receive, both now and afterwards, the full support of His Majesty’s Government."
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But the situation was a bit more extreme then, so a tank might be a bit OTT. Don't know when the army last fixed bayonets except in a parade.
