Haloween and PAP MPs

Just visited Mr Brown’s blog and got a bit confused. He wrote that a PAP MP turned up at a Haloween party and was mistaken for playing the role of a PAP MP. Or was it someone turned up at a Haloween party dressed up as a PAP MP. Which is which?

What I know is that people either dressed up as cut out pumpkins, Frankenstein or Dracula for Haloween. Dressing up as a PAP MP must be pretty out of