Yes, I remember listening to my air band radio as the fog developed across London, but rarely at Southend, so SEN received some interesting diversions from STN, LGW, LTN and even LHR - mainly Viscounts and Britannias, but also Convairs and DC-6s among others.
I anticipate that there will be some A319s, Avro RJs and E-jets diverting into SEN this winter since Southend really is rarely affected by fog or snow. However, no doubt there will be times when the terminal is bursting at the seams due to weather or ATC delays or whatever, but SEN's staff have a reputation for calmness and politeness so I'm sure they will cope admirably.