It's a very simple play on the word elephant. There's Smelliphant (pull a tab and out pops a 'parp' - greatly loved by my four year old!). A poorly, spotty Unwelliphant. A Cinderellaphant (turn the flap and there she is ready for the ball). And of course as the title suggests an elephant wearing wellies - a Wellyphant.
Nick Sharratt's fantastic artwork is perfect for this format and style of book and his sense of humour and the ridiculous can be seen to great effect here. Love it!