It should be there, but you probably need to take the scuttle off to see it. On the nearside wiper linkage, there is a plastic connector clipped to it that holds the sensor, somewhere in this thread there is a way to test it. Have you checked the fuse?
I don't know of any other options, but it is not a MOT fail, as mine passed a month ago with the warning light on. Looks like I'll be trying the clock spring first...