In this cartoon from The Independent by Dave Brown, banknotes bearing the Queen's head are being washed down the drain.
The cartoon is a comment on the Queen's Diamond Jubilee Celebrations. The cartoonist uses a graphic illustration of the idiom 'money down the drain' to suggest that the Diamond Jubilee is a waste of money. The water washing the money down the drain is rainwater—a reference to the rain which disrupted yesterday's Thames river pageant.
A drain is a pipe that carries away dirty water or other liquid waste. In British English the word drain is also used for the frame of metal bars over the opening to a drain in the ground (as in the cartoon). If you metaphorically pour (or throw) money down the drain, you waste it. • Most think that paying rent is money down the drain and it is better to put that money towards a mortgage.
When it was established in 1986, The Independent avoided royal stories. Its founding editor said he thought the British press was "unduly besotted" with the Royal Family and that a newspaper could "manage without" stories that focused on the monarchy. The paper has changed its stance somewhat, but retains a sceptical view of the British monarchy, hence the less than celebratory cartoon.