Ambiguous Ant Puzzle

Ben Sparks
Rob Eastaway and Alex Bellos set this puzzle in the Guardian in January 2016: Basic challenge is: Ants are set up as follows on a 1 metre stick - distances in cm from the left:
  • Alf (A) heading right, starting from 0,
  • B (Bert) heading right from 20.2,
  • C (Charlie) heading left from somewhere between B & C,
  • D (Derek) heading right from 38.7,
  • E (Ethel) heading right from 64.9,
  • and F (Freda) heading left from 81.8
Questions: Who falls off the stick last? What time does this happen? (This is a *simulation* not a calculation, so is prone to rounding errors, but the answer is not calculated before-hand...)