I hadn't heard of Shodan before,
Me neither - I just had a quick peek at their website and saw this on their blog which I found quite interesting.
Quick Statistics on the Router Backdoor on Port 32764 OK so Telecom Italia had the most, but add the UK ISPs together and you can see the UK fairs worse than any other country, and surprisingly the proportion of Zen's representation in comparison to the size of its userbase.
Tiscali-UK will likely be TT Business users as IP ranges for Tiscali-UK are still registered with RIPE but used by TT.
I note users of Shodan can further break down the data to see which routers are most affected - eg with Telecom Italia, these were the DG834G