I would recommend white painted walls. Add accessories that are colorful if you wish. You can change it anytime you want. Depending on the space, I would definitely add something like raw thick tree branch. You can then make some fairy doors on it in color. Interaction with a child making these doors :) I would also choose funky prints of animals over the decals. Or have some animal heads hung on the walls. Children loves cozy spaces canopy is the thin. I would recommend Numero 74. I love their range of colors and quality. Add some cool pillows. If you are into diy, make some. Paint on it, embroider, use different techniques to apply color and texture to the room. Have more than one lighting source: fairylights, floor lamp, etc. If you want something really cool: cover ceiling in polka dots. Don't paint it. You can cut out some cardpaper circles and stick it with blutack. Use different sizes one color rather than having different colors. Take it off when tired of it easily. Enjoy decorating the room :) V

Hi Sonia. Do you have existing furniture to work around or are you buying new? If you go for the neutrals I think you just need to add lots of different textures to add the warmth. If in budget I'd go for a wood floor as that will add warmth immediately but if not add at least one piece of furniture, antique or antique looking might look good. Some gold accents will also add warmth such as mirror, light fitting, picture frame etc. table lamps also give the cosy feel and would add faux stems or flowers and if you have the room a chair. If you want to use the blue perhaps consider using with pale stone'ish coloured walls but adding a blue chair, cushions and perhaps in a curtain pattern but again with some gold, wood etc. You could also add a feature wallpaper such as grasscloth or faux wood panelling etc

Have you looked at the Romo Fabric collection 'Linara' it's available in a huge pallette of colours and they co-ordinate really well with Farrow and Ball paints

I don't understand what 'would be hard to live with' means to be honest. I also agree that advice on this subject is totally contradictory, which doesn't help. The colour of light in a North facing room is quite blue, so anything like a pale grey with a blue tinge will look even bluer. Some people like that, but I personally wouldn't, I find cold rooms depressing. If you want a neutral, then you go across the wheel and select one that is a bit warmer and has some red or orange in and that will create a colour that when combined with the blue light is a neutral. Joa's White, Dimity or colours like that, will look quite neutral in a North facing room. Another option is to go for a more saturated colour such as a yellow, as this can break through the greyness. If you go for a pale colour, then anything like a creamy green could look sickly, so a more definite green would work. If you go for a pale neutral then red based ones will help. I tried about twenty in my kitchen and drove myself nuts! 'Joanna' by Little Greene is a brilliant neutral with a tinge of red in it, that may be worth a look.