Nigel Attwood
has suggested "The Berk Special" looks to be a re-railing train, the right side is the end of a crane with slide out stabiliser visible, the contents of the cage and box are re-railing timbers, steels and the box is probably shackles D bolts etc. Some of the timbers would be used under the crane stabilisers while the steels are fitted together to make load spreaders etc. Berk refers to the stilly berk who derailed the train.