It does seem bad that they are saying that there's no driving examiners available who know how to drive in icy conditions. Aren't they meant to take all sorts of special training to make sure that they are expert drivers, which surely would mean that they should be able to drive in all kinds of conditions? In reality, I'm sure that they're more than capable to drive in icy conditions but it will be elf n safety striking again.

It does say on the DSA website that they won't conduct tests in bad light or bad weather, and the examiners will know therefore that if they don't follow the procedures then they could be held personally liable if someone were to crash on black ice during a test. Knowing how much litigation there is these days, someone probably has sued the DSA having crashed during a test on ice and this is possibly why the guidelines say this.