I've never really studied ladybirds before, and had no idea how many species there are in the UK, but when I spotted this one crawling across the garden I immediately thought it looked odd. Firstly it was very shiny -- you can see in the photo just how much the light reflected off the wing case. What I found really strange though is how the spots are in straight lines across it's back. That really just isn't British! There are a number of websites involved in surveying ladybirds in general and the harlequin in particular. The UK Ladybird Survey is interested in mapping the appearance of the 26 species of ladybird that actually look like ladybirds (including the harlequin). The Harlequin Ladybird Survey, however, is only interested in recording sightings of the harlequin ladybird and produces interesting maps showing the spread of the species over time. If you want to know why both of these projects are important then you should probably read an interesting blog post by Helen Roy which does a much better job of explaining everything than I ever could. And yes, before you ask, I've recorded the sighting with both surveys.
Whilst the entomology may be complicated the photo was actually quite simple. I left the camera on auto, turned on the macro mode and took the photo. Whilst the macro mode on the camera allows me to focus close to the end of the lens it only works if you don't use any of the camera's zoom functionality so I had to resort to aggressive cropping to get the image I wanted. I then adjusted the brightness and saturation a little (using the smart photo fix dialog with settings of -20, 20, -20, 45, 0 for brightness, shadows, highlights, saturation and sharpness respectively) before running the one step noise removal tool.