British action wouldn't have mattered.
( ( British action ) ( ( ( would n't ) ( have mattered ) ) . ) )
(ROOT (S (NP (JJ British) (NN action)) (VP (MD would) (RB n't) (VP (VB have) (VP (VBN mattered)))) (. .)))
It wouldn't have mattered if Britain got involved.
( It ( ( ( would n't ) ( have ( mattered ( if ( Britain ( got involved ) ) ) ) ) ) . ) )
(ROOT (S (NP (PRP It)) (VP (MD would) (RB n't) (VP (VB have) (VP (VBN mattered) (SBAR (IN if) (S (NP (NNP Britain)) (VP (VBD got) (ADJP (VBN involved)))))))) (. .)))