Ash from CRXUK gave me a link to the CTR forum, where they advised using Daisy All Purpose Cleaner (Tesco, 99p for 1L).
1. Dilute 8L of water with 4 caps of Daisy APC - you could add two more caps if it's really dirty.
2. Then with a sponge wipe and wet down the alacantra with the detergent mixture, and a microfiber cloth for the mesh central part. Once the whole seat is done, go over it two more times to make sure I had covered it well and thoroughly.
3. When your satisfied its been thoroughly and evenly done, fill up a bucket with water and get a clean damp microfiber cloth and wipe the seat down, trying to remove the dirt and product. Do this at least 3 times.
4. Finally use an old bathroom towel to start the drying process and soak up any water, and also remove any further dirt that could of been brought to the surface.
5. Leave the seat to dry (it will take a while).
Try and do it on a sunny warm day, but you can always use a blower heater or put it next to a radiator etc...
