Quite often a key factor in any form of nature identification, not just fungi, is whether there is any particular feature that strikes you immediately you see it; on this fungus I was struck by the dark patches that look like bruises. Usually field guides will emphasise characteristic features such as this as well as give the basic details of habitat, season and so on.
In my field guide, the illustrations show that this could be one of several possible species but the fact it did not have gills meant it was likely to be part of a group called 'polypores'. This specimen was in a rather damp woodland so I was pretty sure it was growing on a willow, there were no leaves on the tree at the time but it looked like goat willow (or sallow) to me. That brings down the choice again, but the deciding factor for me were these 'bruises'. They are a primary feature of the blushing bracket (Deadaleopsis connfragosa) and that is how it gets its common name.
The blushing bracket is considered to be one of the 100 most common species of fungus found in the United Kingdom which adds weight to the identification as statistically I am more likely to find a common fungus than a rare one.
Identification in nature often requires logical, systematic evaluation of the facts. Looking at pictures on their own rarely works and killing or taking a sample for microscopic examination is not something that I think should be done except for specific scientific research projects..