My dealer forgot to put the cordless headphones in my new DS ( I purchased the showroom/demo vehicle, so they had been removed)
I went back there today, and naturally they couldnt find the original set, they did however remove a set from a new Evoque which are branded Range Rover.
They work perfectly which is good to know if you are looking to buy a spare / 2nd set.
List price for new Discovery / Evoque ones is well over £120.
Ebay has some new Evoque headsets for £29.

Bargain, so I ordered a 2nd set. 

Do cordless headpohones work with the FL2 Meridian system? Not sure what version it is but the one with lots of watts. I can't go and look in the handbook because my car and I are about a 1000 miles apart. driving on the right side

I would assume it would need the RSE application to be activated in CCF first. MY15
Tyre Pressure Monitoring System (TPMS)
Surround Camera System
InControl Apps soon to be replaced with CarPlay (WIP)
Meridian Premium Surround Sound
Digital Audio Broadcast
Timed Climate
Cruise ECO Data
Follow Me Home Reverse
Extra Features Menu
Picture In Motion
4x4i screen (WIP)
Digital Broadcast TV
Meridian Rear Media with WIFI
Factory Powered Tailgate
Blind Spot Monitoring (BSM)
Reverse Cross Traffic Alert (RCTA)
Electrochromatic Wing Mirrors (WIP)

in my previus meridian systems ( high watt output 780? or whatever) there was no option for cordless headphones.
Most likely because they didnt have dual view.
On the DS, the headphones only work in dual view mode, so with TV, DVD, USB video media.

Its pretty cool.

Kids can watch ( if sat on left of car) and listen to DVD, I listen to radio and can see the NAV 

FL2 has it in CCF but need to be initialised. MY15
Tyre Pressure Monitoring System (TPMS)
Surround Camera System
InControl Apps soon to be replaced with CarPlay (WIP)
Meridian Premium Surround Sound
Digital Audio Broadcast
Timed Climate
Cruise ECO Data
Follow Me Home Reverse
Extra Features Menu
Picture In Motion
4x4i screen (WIP)
Digital Broadcast TV
Meridian Rear Media with WIFI
Factory Powered Tailgate
Blind Spot Monitoring (BSM)
Reverse Cross Traffic Alert (RCTA)
Electrochromatic Wing Mirrors (WIP)