Yes but there are two seperate things at work here, the cost of oil and the tax. Whilst the price of petrol may have fallen since last year this is because of a fall in the price of oil back to "reasonable" levels. A fall in the price of oil does not mean that the tax levied on it should be allowed to increase. Increasing the tax on fuel at times of low oil prices is a very easy way to slip in a tax increase without people noticing, do it on the same day as another major news story and it's even easier.