Upvote:1
If your journey is in a single booking, you will not need to clear immigration. If it's two separate bookings, you will need to clear immigration.
Regardless, however, as a holder of a Swiss residence permit, you do not Need a UK DATV to change planes. If you do clear immigration, you must leave (i.e. the next flight must depart) no later than 23:59 the next day.