So, after all this while, a Freightliner Class 66 came to collect the sitting container. Now, usually, it is an EWS 66 that brings collects the sand from Griffin Wharf so a Freightliner loco is a bit of a change. Freightliner have the main contract for shipping containers into Felixstowe so this is my guess as to what has happened – the Freightliner loco has left a container train on the line and has come in to collect this “errant” wagon. Having coupled up the the main line side of the wagon, it pulled it out and connected it to its existing train. It would then continue its journey to London, as it is on the “UP” side of Ipswich station. (Up being British terminology for towards London). If it was going north, it would have put it on the other end of the loco so that it could go into Ipswich Station and then take the Peterborough line. Correct me if I have this wrong.
In the meantime, the crane situation at the barrier works seems to have changed. here is an up to date image: