Backing paper and toppers are printed off of Joanna Sheen's CD-ROM Victorian Christmas. These were mounted on to gold Mirri card - burgundy red card used for the main card. The card was made by using 2 A4 sheets of card - or if you have tri fold A5 cards then you can use those.
Firstly I scored the one sheet of A4 card in half - this would be the half A4 score line - then take the second piece of card and score at the A4 gatefold line - and then again 2cm`s on from that to make a tab and then cut off the excess card at this point.Take the smaller of the 2 pieces place double sided tape on the top side of the tab - this will then be placed under the larger piece of card so you can`t see the join - this gives you the base of the card.
If you have A5 card with 3 panels then you can do this fold with joining the card - just take the last or first A5 panel and score it in half - what would be A4 gatefold line - this will give you the shape for the base of your card.