This event looks like it will happen from the May timetable change. Although it is only one train per day in one direction.
There is a service in the route planners:
http://www.realtimetrains.co.uk/train/W21294/2015/05/18/advanced
Basically its schedule is:
commence Dover Priory 1033
dep Ashford Int 1056
dep Stratford Int 1125
arr St Pancras Int 1132
omitting both Folkestones and Ebbsfleet.