UK 99 = US 93
:p

I take it that belgian 98 = US 93?

Roughly yes, Europe and Australia use the RON scale where as US and Canada use the average of RON and MON (known as AKI). So because the MON content of your typical European premium is around 89-90 you average out to 93-94.

The one "petrol" that you do have over there that has a high MON rating is the BP Ultimate 102, which has a MON rating of 93 and a AKI rating of 97.

we are at 3300ft here i think and we have 93 at all stations and 94 at some stations.

weird. i thought that UK Gas, at a given octane level had a higher octane than US gas. like 93 in US would be less than 93 in UK. interesting. on top gear they will make fun of the gas in the us for being like watered down and low octane. 'that stuff they [USA] refer to as petrol'

Well we do water it down with ethanol. And because ethanol has a naturally high octane rating they can use lower octane petroleum and still make the average. Europe is just starting to adopt the ethanol trend, some countries now have E5 or E10 like the US has had for the last few years.

yuppers