Thanks Magnetman and Jen-in-wellies. Sorry I can't see how to reply individually! Magentman, yes it does have a bit of pipe sticking down. Jen-in-wellies, we emailed Colecraft to see if they had come across this issue. Gary called us and said he hadn't, but suggested we would need to remove the lining inside the cabin to have a proper look, as you have. Sadly the fitters lined the inside of the boat before they fitted the cupboards, so access won't be easy, especially as the decorative bits that conceal the joins appear to have been glued on. D will need to bring the jigsaw on our next visit. Thanks for this fabulous welcome to the forum!
PS I did find the air vent, we will check this out too, thanks.