I consider myself a fairly flexible worker, but when I moved house recently I found myself with a lot of reasons for home working (waiting for furniture/applicance deliveries) but no capability (internet not yet installed).
I wandered the streets of Turnpike Lane and Wood Green looking for the type of leisurely café that I would easily find in Islington and the like, but to no avail. To make it worse - because I need to work from VPN, and it's mandated by my work laptop - I can't use any wifi that forces you into a walled garden at the beginning, whether it's to make you pay for credit, or to say "Welcome to <insert provider here> Wireless", it just messes things up for me.
In the end, I sat on the corner of a street thanking the lords for people who don't WPA their connection. I also went all the way to Crouch End, where the wireless is just as rare. I did find a pub (typical) called "The Queen", which was a gift. Free wifi, good food and coffee.
Anyway, what brings me back to this is the fact that Time Out have an
article on central London locations that have free WiFi.