Between the summer of 1959 and Dec 1962 when the last Z class banker was withdrawn. Clive Arrow says he spent many a happy hour on these Banking duties in 1960/61. He remembers referring to these engines used for this as 'Ducks'.

This is the eastern, or London side of Exeter St. Davids, at "Red Cow Crossing" with its crossing keeper on the right and a Southern banker awaiting its next call to duty to assist something up the formidable bank to Central station down at the other end.
As can be seen, this was a road crossing, widely used both by vehicles and pedestrians, needing a permanent crossing keeper on this very busy stretch of line , and what an imposing signal box!
4904, "Binnegar Hall" is a local, being allocated to 83B Taunton from the last week in December 1959 until withdrawl exactly 4 years later.