it started as navy & white stripes

If you look at this version www.ipernity.com/doc/philsutters/38619762 you can see, if you have any experience of photo editing or manipulation, that it started from a blue and white striped background and the lines were liquified and sections of the whole were chopped up and turned around and the colours changed as the new section were created. This version's main element was the use of what Adobe Photoshop calls a 'gradient map'. Basically it applies a rainbow effect across the image - or those parts of the image you select. There are a whole load of preset rainbows, with different colour combinations and you try them and see what works best. As with most things like this, it is a lot easier to do, than to explain, as there is a lot of trial and error. Once you start you keep finding controls and filters and effects that you haven't tried before.

Superb
I love excel but I love it even more now!

It was only the first panel of dark blue and white stripes that was created in Excel. That was for a background to a shop-front collage. Then it went into MS Photoshop Elements. I used to use Excel for basic graphics, like posters, as it provided the structure of the grid, but could be used with text boxes and the simple shapes that are common to the MS Office suite. I did some nice tartans in Excel!

Funny! Maybe I can still use excel in the office and call it work. Ha ha!
Its a terrific result although I'm not to good in Photoshop. Went on a workshop some years ago but the tutor said you need to be using it or you'll forget. Guess she was right. Maybe I'll revisit it and find a tutorial. Keep up the good work!