With a spare Nexus 5 knocking about, and somehow too much time on my hands, I decided to flash the phone with Ubuntu Touch.
having tweeted said decision I got a response from someone about an annoying bug which will drain your data -
Seems to have an annoying bug that makes repeated requests to "https://t.co/xT6GOIi3KY". Needs blocking in localhost or you will eat mobile data. It's actually pretty good but needs lots more people to support it.— Marc “I love farmers, me!” Draco FBPE (@marcdraco63) November 30, 2017
I didn't get round to blacklisting the url that night. And when I got up the following day I discovered that not only will it drain your data, it will drain your battery - 13 mb of data roughly, and over 60% of the battery (from a full charge) gone.
So following the instructions on XDA forum, I blocked dash.ubuntu.com -
In 17 hours I've lost only 29% of battery. Massively improved!