Hi Odysseus , a possible explanation is that Ensco have had some problems early on in the piece that have thrown the td estimate date around a bit.
An offshore contact told me that things got off to a bad start,resulting in a company man getting the bullet.Cost big bucks to rectify and cost them a week to fix it all up.
Just a rumour i heard but a fairly good one .
Could explain those confusing dates and estimates.
Cheers Euskal.