What is the official policy on headset collection on International Flights?

On my ORD-LHR on Thursday, about 20 minutes before arrival, the purser made an announcement about removing your headsets and passing them to the aisle for collection. I was still listening to the great tunes on Channel 18 and when the FA came by to collect my headset, I refused and said I am still using it. She said that she was told to and I still refused and she semi-huffed and walked by without it. About five minutes later, the captain makes an announcement about a delay in landing re:weather and that we could follow the progress on Channel 9. Well sheesh, how were we supposed to do that sans headsets!? I continued to listen until we parked at the gate at LHR and was happy not to be met by officers for refusing to obey crewmembers' instructions.

Fast forward to Sunday, LHR-ORD. The purser said that the video entertainment would be turned off in preperation for landing but that we could contine to listen to the audio portion on our headsets - i.e. no collection.

So what gives?