I'm afraid it does.
The mens rea of murder is either an intention to kill or an intention to cause grievous bodily harm for the defendant to have the mens rea of murder. There must be clear evidence of an intention which is proved not only when the defendant's motive or purpose is to kill or cause grievous bodily harm (direct intent), but when death or grievous bodily harm is a virtually certain consequence of the defendant's act.
Gray knew that by walking away death (or grievous bodily harm) was likely to result, thus the intention was clear, making it murder.