Carol,
You and I are in agreement for most of this poem but I do think that de la Mare deliberately breaks the trimeter several times for dramatic emphasis. The effect is still very metric and it works into the flow.
The example below is also onomatopoeic.
and he SMOTE/ upon the DOOR/ again a SE-COND/ TIME; (4)
'is there ANybody THERE?' he SAID. (3)
I do think the American/English difference makes all the difference in this case.
Janet
I've just read all the preceding interpretations of one of the lines. It reminds me of the old actor rehearsing "To be or not to be".
[This message has been edited by Janet Kenny (edited August 21, 2005).]