Turns out that I suck at remembering to take screen shots as I work.
I really enjoyed working on this, I loved how everything came together and how small I was able to make the city. I ended up with a few variations of this design whilst playing with different shades of purple, as much as I liked the block colour and white, I thought it was a little too flat and added some subtle changes to the mountains to give a bit more depth to the image.
This was the first attempt I made at adding bit of depth but it didn't work well for me. I really don't like how the colours don't blend together and wanted to get a bit more of a gradient on the mountain sides to show shadow, but at the same time I just wanted to stick with block colours.
I tried making the mountains different shades of purple to give a sense of depth and really loved what I'd ended up with! I think the different shades just make the image a little more interesting, as well as adding depth, I think this is something that I want to keep consistent across all of my postcards, maybe using an extra 2 or 3 colours to give a sense of depth and distance.