Thanks for the replies everyone - looks like I will have to live with the water marks on the back of the car! :-(
Can I ask how much it cost and where you bought it from? Was it easy to fit? I have a titanium x on order and would like a large rear spoiler in the future... Thanks
In relation to the above question, I actually did a search through one of the online car breakers websites like partsgateway.co.uk (can't remember if it was that one though!) and I received a couple of quotes from different breakers. It cost me £65 inc delivery for a black spoiler in a good condition. Ford wanted over £400 for part and fitting!
It was very easy to fit (I'm hopeless with car modifications), the hardest bit is extending the brake wire and washer line but as the spoiler I bought came with the wiring and tubing from the previous car, I was able to use that and join it together with a soldering iron for the wiring and simply 'plug in' the extended washer tube. The actual removal and fitting of the spoiler is 6 screws and 2 bolts - impressively easy! Start to finish it took me 45 mins.
Please see the below link where there is a full fitting guide that I used. Don't be put off by the overly complicated diagrams - I was tempted to pay somebody else to do it but was glad I saved myself the money and did it myself. Enjoy your new car - I'm very pleased with it!