They are, but it's not a NEMS fitting - it seems to be specific to Hornby. 
  
I just wonder what I should call it. 
  
..though, earwigs seems clear enough to me.. 
  
  
Handy things, even when not fitted in the 'correct' socket - it's easy enough to attach with a small screw and the claws can grip round a bit of the exposed thread.