my 21 month old twins can sing the whole of "god save the queen". I taught it to them by singing it to them slowly when we change nappies or we're bored at dinner. I got the idea from the olympics.
They can also do "row row the boat", "this old man", "twinkle twinkle" and a good amount of "horsey horsey".
What tune shall we learn next?
My dad says "the red flag" or the Internationale to balance out the national anthem!