Speculation or not, there's certainly something fishy going on. In January the pre-pump price of fuel (as delivered to the forecourt), increased by about 10p per litre. The Petrol Retailers Association thought it strange given the relatively low wholesale price of fuel on the world's various markets, coupled with a lack of demand due to adverse weather and the fact that UK refineries were cutting down on activity because no one was buying fuel. They employed analysts to see just where the price increase came from and these analysts could only account for 3p of the increase. They did of course factor in currency fluctuations and all the other identifiable variables but they still came up well short fo the 10p rise.

The main suspicion is that markets are being rigged in a similar manner to LIBOR

That analogy doesn't work as the merchandise exists and actually gets sold directly as shirts and memorabilia, not in futures.
Try again.

Second thoughts ... don't.

I wasn't trying to say shirt sales = "futures" or derivatives. What I was pointing out that there are other markets were the secondary market is far larger than the market which they derive from and no one bats an eyelid.

So what?
That's completely irrelevant to the point now being discussed, which is about paper trading, futures, derivatives i.e. trade in intangibles which allegedly may be rigging the price of the tangible item.

Give it up lad, you're fooling no-one.