Looks like British Gas broke AlertDroid by mangling its certificate chain..
Thanks for your patience while I sort this shit out (rather than BYPASS SECURITY)
EDIT 20150623
EDIT 20150621_2337
Wow, I should probably write about the epic journey to correct the mal-installed certificate..
I can’t update the Google Play Store with the new APK as I’ve misplaced the passwords to the original keystore I used; in the meantime I have built it and put a copy here