Request #407 From Angel

I’m looking for a children’s book, published definitely before/in the year 2004. I don’t remember the title or the author or even most of the plot. All I know is that the book may open with a little boy in bed, who sees a big white bird fly in through his window. The bird carries him to a land where there is a character called Michael Finnegan who rode backwards on a donkey up a hill to a castle. As Finnegan rides, he sings the old ditty: “There was an old man called (or “there once was a man named”) Michael Finnegan, He had whiskers on his chinnegan, The wind came up and blew them in ag’in, Poor old Michael Finnegan (begin ag’in).” Every time Finnegan sings, his whiskers (moustache etc) grow and sink in and out of his face. I know there isn’t much there to go on. If it helps at all, the copy I read was in English (in London, at some point during the years 2001 and 2004) and it was not a book for babies or toddlers, but for children in primary school. Thank you for your help!