We went for 'Sunday Stroll' for our North-facing sitting room on three walls, with 'Fiddlesticks' on the fourth wall, the opposite the window, to make more of the light by reflecting it back from the window into the room. The combination seems to work very well. It goes nicely with a large brass light fitting and we have dark wood furniture in there, but it still feels light- though it has a large bay window.
https://earthbornpaints.co.uk/colours/#colours:
We have to use claypaints in that room (lime plaster)- in a previous house we had a colour called 'Moorland' for the darker three walls on our South-facing sitting room- that's an old British Standard colour that is similar to, but a little a little darker than, 'Sunday Stroll'. Though I;d have picked Moorland had it been possible, now I have seen it in action, in a North facing room, I think Sunday Stroll works better than Moorland would have done.
Earthborn do proper sample tins, BTW, if you ever use their paints it's definitely worth getting one before you commit, as claypaints do take light differently to standard emulsions. Claypaints let walls breathe, cost more, lower sq m coverage, but needs fewer coats. Not hardwearing or washable, but the surface is like velvet and disguises irregularities in plaster better than standard emulsions do. Gorgeously easy to put on.
I use Dulux Absolute White Light and Space (trade) matt emulsion on ceilings. L&S paints reflect light better than any paint I have ever used, even if matt- great where you need to make most of what light there is in a darkish room.