I agree. However, no modifications bar replacing the glazing and (non original) telephone and associated wiring will take place. oh and the installation of a brass door lock!
The actual internals of the proposed "kiosk" are modular and are not affixed to the phone box. According to the planning app, the internals can be removed in minutes leaving just the phone box.
What I'm more interested in is have these people bought the phone box and/or the land on which it stands. How does one go about deciding: "I want to turn that phone box into a coffee kiosk".
Modifications aside - which seem sympathetic enough - I would rather it remained as a working phone box. There aren't enough phone boxes any more and, as someone who chooses not to have a Mobile, I do occasionally use still use them when out. There must be 50 outlets within a two-minute radius selling coffee but probably only one other phone box.
If all the additions are reversible and non intrusive then I don't see the problem.
If you are caught short without a charged mobile or don't like mobile phones, then there are comfortable shops all over SE1 for international (or other) calls or people can ask friends or hotel front desks or shopkeepers a favour.
The only well maintained phone boxes are the ones that double up as huge illuminated advertising billboards right next to the kerb and therefore traffic.. the rest are loss-making and barely maintained.
Re-use of the one in front of the Heygate in a similar fashion would be great news.