Sure the crude price would rise again as demand rises, but not all the way back. Firstly, demand for all oil products won’t return to normal levels for several years - not least reduced demand for jet fuel, and other oil products used in industry which will take a hit in line with economic activity. Secondly, road fuel use will take a while to get back to normal - again in line with the loss of economic activity (and of course this will affect the extra revenue an increase in fuel duty would bring). Thirdly, pretty much every storage facility worldwide that can take oil products (including crude) is currently full. That excess supply will take several months to unwind, and will further suppress the price. The oil price won’t be back above $50 for a long time. The oil futures 18months hence are only at around $35.
I fundamentally disagree with you about fuel duty stifling the economy. It rose almost every year through the 80s, 90s, and 00s, during which time the economy more than doubled in real terms. Fuel duty has not risen since 2012; had it risen simply in line with inflation since then, the government would have another £12bn a year to play with now.
Well then if 'road use fuel' will take a while to get back to normal, then even '7p' on a litre wouldn't bring in the '£4bn a year.'
Fuel duty increases hit everyone, including the poorest, either directly or indirectly.
It only disproportionately hits against those who do lots of miles, and those in the niche specialist sports car industry and its well off patrons; oh and of course the poorer working classes in semi-rural places far away from our metropolises who over the last 4 decades have suffered from a lack of government support for their strategically important heavy industries, such as ship building, steel industry, some of the locomotive building towns, coal mining, heavy industrial etc. Maybe some extra tariffs on far eastern steel etc. would help here if the government wasn't scared of us having to weather a storm in prices of goods coming in, in order to protect our strategic ability to be able to negotiate in the future based on our heavy industries still existing. I think fuel duty hike of 7p would be another undeserved blow for the semi rural communities.
In a way I could see the rich in places like suburbs and cities being able to mitigate against high fuel duty hikes by buying the most expensive electric cars whilst those out in the regions are stuck with their second-hand, old cars, with the ability to refuel quickly a necessity miles in the sticks.
I would argue that the economy rose through the 80s, and particularly the 90s and 00s (pre crash) despite, and not because of fuel duty hikes. I would presume the economy rising would be down to unsustainable levels of immigration fuelling growth, booming aerospace and motor industry (albeit sadly foreign owned), cheap imports of consumer goods, cheap global food prices, electricals, and industrial goods, and fairly cheap government borrowing because of impressive GDP figures. And also because of innovation and robotics in factories / good productivity improvements pre 09 etc