A few months ago, there was an accident at MAN when a taxying aircraft hit the tail of a bmiBaby 737 holding for runway 24L. At the time there was some criticism of the 737 crew, which was a little unfair as they were stationary at the time.
In the ensuing discussions, it was made clear that there is nothing in the ANO or UKAIP to insist that an aircraft cleared to a holding point is obliged to pull forward all the way to that holding point.