Quick update though I won't post the exact email here (no time to ask for permission - it's almost 5!).
RSPCA have been involved and the people attempting to rescue the cats aren't sure what the RSPCA have done with them (i.e. PTS or helping with homing).
They are trying to find out exactly what has been done.
They are not allowed back on the property to see if there are any more needing help ;(