Knock knock...

"Who's there?"
"Big Horse"
"Big Horse who?"
"Maybe it's Big Horse I'm a Londoner..."
"Big Horse"
"Big Horse who?"
"Maybe it's Big Horse I'm a Londoner..."

http://www.vocalvoices.gripsky.co.uk/
http://www.vocalvoices.gripsky.co.uk/viewtopic.php?f=15&t=6300