I don't believe that SOU hours are similar to SEN as SEN is open 24/7. Delayed inbounds to SOU are normally only accepted up until 23:30 and then only if ATC, Fire Service etc. are available. After that they usually divert.
From the Southend website:
Southend Airport has always been operational 24/7. As part of the S106 planning agreement (2010), the night period was extended from midnight – 06:00 to 23:00 – 06:30. As well as extending the night period, a number of tighter restrictions at night were implemented;
The night quota was reduced from 940 to 120 night flights per month
- Private helicopters were banned at night
- Only aircraft with a noise QC level of 1 or less may operate at night* see below
- Passenger flights can only be scheduled between 06:30 to 23:30 (limited quota between 23:00 – 23:30) however delayed and diverted passenger flights may still operate.
Those last 9 words are the crucial difference.
LT