Re the wheat/gluten/soy/dairy/nut-free 'alternatives'. I used to get lunch near Covent Garden from a Morocan place who did wheat/gluten free savoury (roasted vegetable muffins) and sweet muffins (berries etc) which were delicious.
I am not allergic but have food intolerances so even if they are baked on the premises, it would not be a problem for people like me but would really help.

I also would love a place selling lunch based on the "tiffin lunch" basis, i.e. you get your lunch in a reusable container which you bring back the next time you get lunch. (You would pay a deposit for the container).