A 'Green wall' perhaps? A bright paint colour?

Hi

Ditto on the screen to the wall. A dark patterned one installed would make the staircase contrast. Something like this from Bunnings....

Do you, or anyone you know, have any artistic skills? You could paint an image onto the wall, blending the handrail of the staircase into the image. Tromp l'oeil to suit the personality you want to have whilst sitting at your office window.

Thank you everyone for the suggestions.

I'd put a vertical garden on the wall to soften the hard concrete surface area

Your quickest, cheapest option is window frosting - there are some beautiful patterns in graduated frosting that would hide some or all of the stairs/wall while still letting in loads of light.

I agree with the others. Decorative screening on the window side of the staircase would block the view of the staircase. Painting the wall using a relaxing colour and adding plants would give a calming effect when looking out from the office window. You could brighten up the space under the stairs by adding a few pot plants. Ferns grow well in shady places.

Geraniums or pelargoniums in moderate pots on end of each stair tread - seen it in France, looks great, and they cope with shade or sun.

get a large pot, place it under the stairs, after you have planted a flowering creeper plant in it. Paint the wall white, or light green, then add wires / mesh so the creeper plant will be able to grow up and along the wall. I would buy a plant that is already big enough to bring the bulk of the foliage out from under the stairs so that it already has light and to start with you may need to manually tread the plant through the wires / mesh until the plant establishes it's self.

The only problem I see with placing plants anywhere near the steps, if leaves fall and are not cleared away, they will rot and become an eyesore as well as slippery if stepped on. Also it may reduce the space as the plant/s grow, as you use the steps. I think placing screens against the grey wall in a fancy pattern would look nice and is basically maintenance free. I would also paint the steps, maybe in the same shade as the screens, though I would leave the railing as it is closer to the window and you don't want to make it the feature.