There a quality GBP discussion going on Motley Fool....They don't rate the Uganda-GBP upside nearly as much.
The potential upside is a guessing game. FWIW I prefer to look at company estimates of most likely structure sizes and put a conservative value on them. That doesn't exclude the possibility that the structure is bigger than assumed and it doesn't give much weight to de-risking of analogous prospects - which, after the drilling of the initial well, it might be appropriate to do.
The duster downside though is easier to quantify ;-)
ee
GBP Price at posting:
28.0¢ Sentiment: ST Buy Disclosure: Held