long - 1659678
medium - 1659677
short - 1659676

3rd from the back is a 'long' one.

careful when you put the new one on or it will break straight away! i've found the only reliable way is to file or Dremmel the little gripping fins back on the inside of the clip, just enough to make a snug but not tight fit over the sill seam.

oh... and they are £3-odd each!!!