Mon-Fri times for the 3 local airports are as follows (although do change by 5-10 minutes depending on the week)
Outbound departures:
MME: 06:20, 10:10, 17:10
NCL: 06:00, 09:15, 11,10, 13:25, 17:30
LBA: 06:20, 09:10, 13:25, 17:20
Inbound Arrivals:
MME: 09:40, 16:40, 21:30
NCL: 08:35, 10:25, 12:50, 16:40, 22:20
LBA: 08:35, 12:45, 16:45, 22:15
It would appear that an early afternoon departure would be the most likely as thats what NCL and LBA both have. NWI is on 4 rotations and they have a 14:10 departure too.
I appreciate that MME is more of an outbound airport but I think that an early afternoon flight would work well for visitors who could do a lunch-to-lunch meeting in the Teesside area and then get home at a reasonable time. I know my European colleagues would prefer this than getting the 5pm flight to AMS and getting a connection which gets them home at midnight.