I've looked at that link and to be honest, I don't know where them figures come from.
Like I said in my original post, my missus keeps a record of all the petrol she puts in her car - her book dates back to 1992. Petrol is prob about average price here (compared to the rest of the UK) and my missus always shops around for EVERYTHING to get the best price. If she was paying 64.9p per litre in 1997, I can assure you it wasn't on sale for any less than that - not round here anyway .......