http://www.britishairways.com/cms/global/pdfs/handheld-devices-used-onboard_Dec14.pdf

Their policy is if it's not allowed, it's forbidden.

Allowed items:

Mobile Phones/Smart phones
Laptop/Notebook computers
Tablet computers
e-Readers
Noise-cancelling headphones
Portable DVD/CD Player
Digital Audio/MP3 Player
Bluetooth Devices
Electric Shaver
Personal Cameras
Electronic Games
Assistive Medical Devices