Corrected entry: At the end of the movie, Sefton escapes with Dunbar. In response to the question "I wonder why he did it?", Animal suggests that "Maybe he just wanted to steal our wire cutters." In reality, escaping prisoners would never take the wire cutters through the wire with them. They were too hard to replace. After cutting the wire, the procedure would be to hide the cutters inside the fence nearby at a prearranged spot to be retrieved later by the prisoners and then reused.
Jim Mayer
27th Feb 2016
Correction: It's possible Sefton did leave them behind. It's also possible he kept them, simply because he wasn't aware he needed to leave them. After all, it as a spur of the moment decision to allow him to be the one to escape.