Just after some thoughts as to whether thsi would be considered, as raised by a client (ImageEditor > Transform > Flip) functionality differs to other image editors like photoshop, paint, windows image editor.

The behaviour seems to differ to most other image editors. I can see that it is flipping on the vertical and horizontal axis, however other programmes seem to flip the image as you see it.

Untouched

Flip Vertical - Flips on the vertical plane

Flip Horizontal - 

Example of Windows Image Editor - Flipped Horizontally