Why has our organist got green hair?

As many will know, our young people's choir recently gave 2 spirited performances of 'Matilda'. It was a demanding task, performing in a small church with none of the usual theatre facilities and improvising a range of props and special effects. The children put their hearts and souls into it. They entertained the audience and raised money through voluntary donations for the church and the charity 'Young Lives versus cancer'. At some point Stephen made a promise that, if all went well, he would wear Mr Wormwood's green wig at the next service, which happened to be Harvest. Well, Matilda was  a great success, and you can't break a promise, can you? So .....