Ok, the debate is heating up. I don't value lounge access for this trip. My top priority is being able to leave the Intercontinental Hotel as late as possible to catch a flight at 1900 (either at LHR or LCY) with low stress and as few things as can go wrong as possible. So, considerations are the travel time from hotel to airport and time between leaving the transport (train/taxi) and being at the gate. So security line wait could be important.

With those clarifications, do the LHR guys still prefer it to LCY under these circumstances?