Wasn't this the unit which had aircon problems, mentioned in last week's Channel 5 programme?
I've checked the recording of the programme and vehicle number 56904 is clearly visible, so yes it was 180104. Indeed I was on that train that evening (I appear in shot for a couple of seconds but I'll keep when that is to myself!

), the
TM▸ apologised more than once about the lack of a/c but I was standing in a vestibule anyway.