I'd suspect we were the ones who introduced Monitor to SOCA, and...

I'd suspect we were the ones who introduced Monitor to SOCA, and hence got a discount as part of a 'finders fee'. Plus Landau quite clearly negotiated us a better deal than Monitor got. At the time we had 3 projects (Texas/Georgia/Puntland), and Monitor had 1 (a prospect that was, and still is, underwater). So Monitor were clearly desperate for another project and their desperation would have been reflected in the increased price- we were less so and so were able to get our slice cheaper.

That's why the final price we pay for an increased stake/the whole of Trinidad will depend largely on how desperate the owners are to sell up. They'll know the assets are worth a fair bit, but they're old, and after all this time, might just want to get rid and will accept a lower offer.