No, because you are creating the need for a 'humane dispatch' by an illegal act of shooting during the prohibited 'darkness' hours.
But, if you are out doing a spot of fox control, and come across a roe buck trapped in a fence in December, then it doesn't matter what time of day it is, it is then HD as even if you were able to cut it free, the chances of it dying from stress/shock etc is high.
You can't use 'animal welfare' to try and cover your arse for an illegal act, nor should you put anything shot under HD into the food chain, as it's not shot by legal hunting methods.
And guys, if you had a .22 conditioned for 'rabbit' only, but used it to do the right thing by putting a suffering animal out of it's misery, do you really think that you'd get prosecuted for breaking a condition ? No, your more likely to get prosecuted for allowing the animal to suffer by NOT dispatching it.