The trigger for the concern was the Shell tanker drivers winning a 14% pay rise....
Tanker Drivers Strike
Inflated fears of a 1970s comeback
Shell settlement triggers fears of summer of discontent
"This really is going to sound some alarm bells in Downing Street," one said on Wednesday night.
Talks to resume in Shell dispute
By Sunday, more than 600 of the 8,700 petrol stations around Britain had run out of unleaded and diesel fuels.
Oil giants in spotlight but it could get much hotter
Shell's insistence that it is not responsible for the bust-up between tanker drivers and the contractors it uses has not stopped it being dragged under the spotlight.
Only Shell can solve tanker drivers dispute: Len McCluskey of Unite Union
Len McCluskey, assistant general secretary of Unite, said: "Only Shell sets the terms of this contract and only it can solve this dispute. This is one of the most profitable companies on earth and it now needs to provide the financial flexibility to avert this dispute."
Petrol crisis looms as Shell faces drivers strike
Fears of a new petrol crisis have deepened after lorry drivers for Shell's suppliers announced a four day strike.