Like Urmstogran I learned the words of Jerusalem at school where it was sung with great gusto. Land of Hope and Glory was a firm favourite and yes, together with Rule Britannia I do know all the words.
However I cannot claim to know more than two verses of the National Anthem, and I wonder if it is a generation thing. My mother, when in her 80s could still sing not only every verse, but also those of the Welsh National Anthem in English and Welsh. Her father was born in Wales but from an English family, and such things were important to him. Perhaps I come from a particularly patriotic family, who knows?