Interesting thanks. Looks as if Cityjet is in trouble then as the planning permission states:
From 31 March 2017, no AVRO RJ100 type aircraft (or any variant thereof) shall operate from the Airport at any time unless it has been demonstrated to and approved in writing by the local planning authority that noise from such Aircraft does not exceed the maximum noise levels specified in any approved scheme under Condition 18.
I think this is better discussed in the LCY thread, so I will move the topic there.