The 'midnight express' from AMS to the Caribbean is indeed westbound. Only other things around at this time that may cause restrictions are the usual insomniac's:Tommy's travel, etc.
These however are usually minding their own business.
It's track is usually Thames estuary Lands Endish but it does seem to stay below 300 the times I've seen it. Infact, it passed over Swanwick at 260 this week.