He was waiting for the Scotland Yard men. 
( He ( ( was ( waiting ( for ( the ( Scotland ( Yard men ) ) ) ) ) ) . ) )
(ROOT (S (NP (PRP He)) (VP (VBD was) (VP (VBG waiting) (PP (IN for) (NP (DT the) (NNP Scotland) (NNP Yard) (NNS men))))) (. .)))
He wasn't waiting for anything.
( He ( ( ( was n't ) ( waiting ( for anything ) ) ) . ) )
(ROOT (S (NP (PRP He)) (VP (VBD was) (RB n't) (VP (VBG waiting) (PP (IN for) (NP (NN anything))))) (. .)))