I thought I had read that bluetooth was ok at any time, but the latest thing i can find says can be used apart from during taxi, take-off and landing
https://www.britishairways.com/en-gb...ation-and-faqs
http://www.britishairways.com/cms/gl...oard_Dec14.pdf
Bluetooth accessories
All Bluetooth accessories (for example wireless keyboard, headphones, etc) may only be used during the flight but must remain switched off for taxi, take-off and landing