Rofl how can you consider it a cut, it hasn't been cut and they have been making more and more revenue from it as the price has risen. There is no way you could consider it a cut.
The magic words are "The real world". OK, break it down, this might sound patronising so apologies if it does, I'm trying to pitch it for all readers and to keep the maths nice and easy to work with, and obviously simplifying real-world economics to simple numbers. I lose track of what will make sense to people who don't do this stuff all the time, so, this probably won't be pitched quite right- but bear with me.
You have £100 in your pocket. The rate of inflation is 5%. Today, your £100 has exactly £100's buying power. But if you leave it in your pocket for a year, that 5% inflation impacts the price of items. If you go to the shops with your £100, things that cost £100 last year now cost £105, and you can't afford them- you have the same amount of money but it buys less.
If, on the other hand, you put your money in the bank at 5% interest, then take it out in a year, you now have £105, but you're not actually any richer, because the rate of inflation exactly matches the increase in money- buying power remains the same. The total amount of money is actually pretty meaningless, because the
value of money changes.
(this is a sore point for me- I used to work for a bank where we had several "savings" accounts with 50% below inflation interest rates, so people putting money in there were literally losing money year on year. Yet they were always convinced that they were carefully saving and that they got an extra 2p to the £1 every year. Their £1.02 next year was just worth less than their £1 today)
So, anyway, take this basic fact of inflationary economics (probably the most fundamental fact of all modern economics) and apply it to tax. In the case of fuel tax, they get more revenue but the buying power of that revenue is not the same.
£100 in 1998, say, now equates to £135.42, according to the RPI ( a very effective inflation gauge). So tax (or savings, or income) have to increase by exactly 35.42% over that timescale in order to keep the real world value the same. I'm going to stick with this example as it's a nice easy timescale to work with
What Dolph is choosing to argue, for whatever reason, is that this doesn't actually matter. He states that if the government increase tax by less than this, it's still a tax increase. And in a sense, that's right, because the percentages do go up- but the real world impact doesn't reflect that, and to be blunt everything apart from the real world impact is completely meaningless.
The impact on your wallet is actually less, you are left literally richer, you can buy more stuff. The government gets more money in simple terms, but because of inflation in the mean time the amount of money they get is actually worth less, so they are left literally poorer.
The only way that this isn't a decrease, is if you ignore all of this completely, which you just can't do when dealing with a real-world economy. Real economics actually deals with the real world impact instead of just percentages on a screen, which is what Dolph's done here, using gross numbers to spin a totally false picture. An increase in tax, or earnings, or savings which exactly matches inflation is a 0% net change.
If you want to break it down even further, it's like walking against a treadmill. Inflation is the speed of the treadmill. If you don't walk at that pace, you fall behind. These tax "increases" are walking slower than the treadmill, and falling behind.
He's also wrongly assumed that I'm in favour of lower fuel tax, and that I vote labour, but that's by the by

If you're going to counter a policy, though, you have to know the facts. The anti road tax movement's argument is perfectly sound but they're arguing it with terrible maths, it's populist and simple but it's fairly meaningless. If you want to change anything, you need to know where you stand now. But a lot of people would sooner cling to the wrong numbers, which are simpler to make their case with.
<an edit for that last point>
I actually have no idea what the exact taxation position is now when you compare the first day of Blair's regime with today. At the peak of the price rises, overall corrected tax inc VAT was certainly higher than it was on day one. Not drastically higher, but still higher. It came down largely to the early years when Brown carried on the Tory fuel tax escalator, and actually increased it for a while. This was really frustrating, because people were making good arguments in favour of fuel tax cuts based on wrong numbers, which they could have still made with good numbers- instead of saying "This government constantly increases fuel tax", which was wrong, they simply had to say "Since this government came into power fuel tax has increased", which was completely true and makes the same argument.
I've not checked the numbers since the peak prices, so I'm not sure what's happened there. It'd be interesting to know what the changes in VAT and duty have now done- the rates are up IIRC but the values might be down, if the price drop is high enough. It might be that the total-term tax situation is still up, as it was at the peak, but it might be a little down now.
Brilliantly, the 2000 fuel protests which everyone was so pleased about actually came AFTER the abandonment of the fuel tax escalator, and the start of the downward trend of taxation- they were protesting against the most positive motorist's budget for nearly a decade. This is what I mean about bad maths. Now, if you ask a typical driver he'll tell you it actually led to a cut, because that's what people remember. Well done protestors! But if you ask a government official, they'll tell you what actually happened, and can point to the exact dates of changes, and if you've just based a campaign or petition or argument on a false assumption, he'll then ignore you. Your actual argument re impact on retail prices from hauliers, impact on remote communities, etc etc might be completely valid, but it's just as important that you make your case.
See also:
the only concessions the public have got have been the results of mass protests (in 2000)
Cause comes BEFORE effect.
<edit over>