Painting outside walls

[car1sberg]

Hello. We've not long moved house & the walls in our new back garden look like this. We'd like to remove the flaking old paint and repaint it (just DIY) - what is the best way to do this?
I've heard use a wire brush or use some of chemicals to dissolve the old paint?
Thanks!

I would jetwash if it doesn't cause too much damage. This is what our decorator did before repainting our house. We are weighing up hiring a jetwasher or buying from Screwfix for our next project.