Leech or Flatworm?

Leech or Flatworm?

Observation - Leech or Flatworm? - UK and Ireland. Description: This roughly 2cm critter was left behind after Ducks where resting on footpath. it seems to have segments which makes me think Leech but this is my first interaction with either Flatworm or Leech. i couldnt stop to collect. the critter seems to be eng

This roughly 2cm critter was left behind after Ducks where resting on footpath.
it seems to have segments which makes me think Leech but this is my first interaction with either Flatworm or Leech.
i couldnt stop to collect.
the critter seems to be engorged on blood and has white spots down the sides.
Video: https://youtu.be/WdDtv1OJhYs