"But then losing comms would effectively shut the airport with its traditional tower too.
Not necessarily, good egg.
The airfield I worked at had an 'ECU', an Emergency Control Unit. It was a 'Portakabin', located a considerable distance from the control tower, from which an Aerodrome/Approach Control Service could be provided in the event of the main facility becoming unusable.
Many years ago, contractors had to remove asbestos from the control tower building and many of us provided Aerodrome Control from this facility for an entire week-end.
I believe EGLL has the digital equivalent of this facility today......In my book, an acceptable use of this technology.
Many years ago, a comms failure at EGNX resulted in one of the ATCO providing a very limited service using the radio in a light a/c parked in front of the tower.