plusnet IP address 212.56.71.212 - google proxy? what gives?

[#1]

I see from my OpenWRT connection logs unexpected port 443 connections to a plusnet IP address (I just reconfigured my network and so am using plusnet DNS for the moment).  Reverse DNS yields nothing useful and I see from using currports on the Win7 host which is originating the calls that they are coming from google chrome.  Putting that IP address into a web browser gets a google search engine. 
Is this a google proxy located at plusnet?  How is it implemented - DNS poisoning?  What is the reason for it?

[#2]

probably this http://community.plus.net/forum/index.php/topic,121162.

[#3]

Quote from: Kelly

https://peering.google.com/about/ggc.html Google devices which serve cached video content etc.  All that content is already served from caches across the internet, it's just closer to the customer with these devices.

[#4]

I guess so - I've seen a couple of other addresses listed too with the same behaviour.  A bit slack not having the reverse DNS set to something meaningful if so - I treat any IP I see without it as a bit suspicious.
If it is being done via DNS I'll probably switch away from the plusnet DNS servers again.
For example, if these are GGC boxes then clearly identifying them as such from the reverse DNS would be polite.