All joking aside, everybody's remarks about the fallibility of HCS/NAS is actually the reason why the ATSAs should be taking a look at backup scenarios for EFPS. If EFPS is to be linked in any shape or form to NAS then the potential for calamity should be self-evident.
This would be of particular importance to EGLL, primarily because ATCO control of this airfield presents a far more complicated overall scenario than at any of the others. If the ATCOs have lost their primary source of information, the info on EFPS - linked to the ever-so-reliable NAS - then where is the info going to come from, and in what format, so as to allow the job of controlling the live traffic to continue?
The ATCOs will have their hands full - so who's going to be tasked with providing some sort of backup/info supply if it isn't the ATSAs?
To all those who have expressed a view that this is just ATSA scaremongering, and EFPS is a reliable piece of kit, I would only say that, in the case of NAS, you should all look at the track record. If EFPS is in any way linked to NAS, then emergency contingency most certainly should be on the agenda, and especially for the new EGLL tower.
Hindsight can be a wonderful thing - it can also be very painful.