That design is called Damask. It's been getting really popular in the last few years since Martha Stewart's Weddings magazine came out with a cake in that design a while back. (See below.) There are cutters, templates and stencils now available for either cutting out the design piece-by-piece in fondant....or even using stencils with air-brushing, buttercream or royal icing!
Lots of options, just check out Google Images and threads on here. (Here's one from recently.)
There are also chocolate transfers that have that pattern. That might be your best bet.
Antonia74 and AlamoSweets thank you for the info.
What worries me is that this is going to be a black cake with white "damask" on it, not sure if it will be all 3 tiers.
Looks to me that this is going to be very time consuming and intricate, not sure whether I see chance to face this challenge.
I will email this bride this morning and see what all she has to say.
Many thanks once again
here is a website where they sell the stencils.