the problem with the Festive Events appears to be that there isn't sufficient time between the lunch event guests finishing up and leaving, and the evening guests on first dinner arriving for alloted check in at 1540/1600, so everyone is held up and delays built up with the result that diners for the 1800 sitting were still turning up at 1820, and so on. The second sitting was pushed back 30 minutes to 2030 as a direct consequence.