Motorists should be braced for a diesel price rise of around two to three pence per litre in the next fortnight in the wake of the Brexit referendum.
The price rise will be justified as compensation to oil companies for the drop in the value of Sterling post-Brexit.
"We’ve done the maths and crunched the numbers. Any rise above three pence a litre to reflect currency movements is just post-Brexit opportunism," says Quentin Willson, lead campaigner for FairFuelUK.
Rumours circulated last week that an eight pence per litre rise was being considered by one supermarket chain, while the price of bulk diesel for hauliers was being quoted with a five-to-six pence per litre rise.
But Howard Cox, founder of FairFuelUK warned that "maximum pump price rises should be no more than three pence to ensure retailers’ margins are similar to pre-Brexit levels."
The AA agreed: "We’re not seeing anything to suggest anything other than a two to three pence per litre rise is reasonable."
Typically, a rise that responds to a move in the market takes 10 to 14 days to work its way through the system.
"And we should remember that we still have five pence per litre to get back to where we were last year," added the AA.
All campaigners are agreed that a bigger rise will reinforce calls for an official government fuel price regulator, which FairFuel dubs ‘OfPump’.