For Tim Carter the reason I think for the transition in the words to head chopping may be because as a child we used it as a rhyme for a childrens game (cf the "game of selection" in the movie "The Wicker man") in which 2 children faced each other and joined hands as an arch and all the other children form a chain and passed between them. All sing Oranges and Lemons and the candle/head chop verse, as eachchild passes between and under the arch of hands the hands are brought down to waist level and raised again until the chip chop chip part and the person imprisoned was the chosen. BTW St Clement Danes is only a few hundred yards from Covent Garden which used to be the main fruit and veg. market for London. St Martins is "in the Fields" in Trafalgar Square. I bekieve the game may be set out in more detail in Iona and Peter Opie's" the Lore and La nguage of schoolchildren" if you have difficulty finding this excellent work on childrens rhymes and games please feel free to contact me as I have a copy somewhere( this goes for anyone else also).