We have changed the London xt lights from 08/2022 so if you bought your London light before August 2022 you will need the 25mm size big.
If you purchased the London xt lights after August 2022 then you would need the small 21mm.
This only refers to if you have the London xt lights, if you are purchasing for the Durham or canterbury it is still the same so it will be big 25mm.
Its 12 lumens
The replacement top will have a pre-installed battery.
Once that white cap is removed, there is a screw and battery case underneath, undo that screw and there is the battery.
Correct, they are under the white cap, you unscrew the battey holder box and then replae. AA battery 1.2v.
It is white in colour.
The diameter is 78mm, these are designed for out XT range of lights.
The replacement tops are the same version as what you have on the Durham lights.
2 x 600mAh NiMH rechargeable batteries per unit.