The preparation requires cutting coloured card into neat squares and rectangles - and also cutting out the tree shapes. And, after a comment from someone, I have concluded that I have done too good a job on the latter as it was thought that I had bought them ready made, and I have done a little more preparation than that :)
Also - I did the preparation for the first Sunday of Advent, that being today -
I took the picture at 3.30pm yesterday when I had taken the candles up to church and put everything in place. It was almost dark, and I only bothered to put on the Sanctuary lights - I rather like the effect.