The banks have nothing to do with the cost of commercial rent around old street roundabout and the shoreditch triangle. It's expensive because all the silly startups now think they need to be here to sound credible / look cool / etc etc so landlords can charge these prices and people will pay. Infrastructure wise, the area is a mess. Fibre coverage is spotty at best. ADSL seems to be pretty crap. Most buildings are poorly converted from storage/etc into office space.
On the plus side we have nice places to eat, drink and get coffee so it's not all bad I suppose. Also the commute is pretty good for east london folk.
Also side rant. To all non-londerners, Tech City / Silicon Roundabout is an abstract concept that doesn't actually exist in any concrete form. Unless someone told you, you wouldn't even notice you were passing through it. Infact the only remotely "tech looking" building is satellite company Immarsat's HQ office, and IIRC they were around long before "tech city" had been dreamed up.
I think they meant "next door" in the sense that, someone consider where to work would probably go to the big banks as opposed to the lower paid startup "next door".
Also side rant. To all non-londerners, Tech City / Silicon Roundabout is an abstract concept that doesn't actually exist in any concrete form. Unless someone told you, you wouldn't even notice you were passing through it. Infact the only remotely "tech looking" building is satellite company Immarsat's HQ office, and IIRC they were around long before "tech city" had been dreamed up.