SON Handlebar Switch for Ladelux - 40 cm

I recommend this product

Used on London-Edinburgh-London & worked perfectly with the Ladelux (reviewed separately). I mounted it centrally on drop bars where I found it easy to access & view. Worked wearing neoprene gloves (touch screen type not tried but I presume they would work too).
Easy to see what setting you are on and whether charging or not.
My light was fork-crown mounted and the 40cm length was fine for that (the 20cm alternative would not have been). Mounting outboard on flat bars may be a struggle as currently there is no longer option or extension I know of.