Had actual experience of this many, many years ago.
Was supposed to meet a passenger at Gatwick, which was reported closed due to foul weather. Most flights were diverted to Stansted.
Quick phone call to company Ops confirmed the diversion. Picked up amazed but admirative Pax at STN (no mobiles in them days to let me know!!)
STN closer to home than LGW by a good 200 miles round trip.
Took the trouble, and I think it is important, to mention to ground staff what we were doing. They were grateful - said it would have complicated their head count on the bus had we not alerted them.
All baggage re-united with Pax at STN, I think for customs reasons. We can't have uncleared baggage roaring up and down the M11 can we?