I believe none of the CRJ series of aircraft are approved to operate at LCY. Only the following aircraft are approved to operate at LCY:
Airbus A318
BAE 146/Avro RJ Family
BAe Jetstream 41
ATR42
ATR72
Bombardier CS100
DHC Dash 7
Bombardier Q Series/DHC Dash 8
Dornier Do328
Dornier Do328JET
Embraer 135
Embraer E170
Embraer E190
Fokker 50
Fokker 70
Saab 340B
Saab 2000