Turns out the screenwash pump had died. Changing the pump cured the problem. Of course the job wasn't quite as simple as that sounds. Minor aggravations along the way included the following: 1. Unused as I am to modern cars, I was shocked to find no jack or wheel brace in the boot. I don't know why I was surprised: they hadn't given me a spare wheel (just a bottle of get-you-home sealant) so why would they need to provide the means to change a wheel? Fortunately, I have a trolley jack. Oddly, they HAD given me a little plastic grippy thing for removing the plastic covers from the wheel nuts. I also discovered they had provided an electric air pump that runs off the 12V lighter socket, which is smaller and lighter than my existing one, so I can retire mine now. Thanks, Skoda! 2. When the fault first showed itself, front and rear WIPERS still operated, although the WASHERS did not. Then the symptoms changed, such that the rear WIPERS also did not operate. I re-checked all the relevant fuses and found nothing wrong. I still don't know the reason for this. The rear wipers worked again after I changed the pump. 3. Before changing the pump I thought I would just check that electricity was reaching the pump. I pulled the connector off the old pump, switched on the ignition, held a voltmeter to the two terminals in the connector, and had an assistant operate the stalk controls for wash-wipe. I didn't see any voltage across the terminals. Aha, I thought, it's a fault in the wiring, or in the stalk controls. I was about to call a garage, but on a whim, I connected the new pump electrically and repeated the test. The new pump ran. Moral of the story: a voltmeter might not be the preferred way of checking for voltage?? Maybe my probes weren't making proper contact, who knows. 4. The front WIPERS do not operate if the bonnet is open, although the washers do. This confused the post-replacement testing. Presumably this is a safety feature to prevent the wiper arms from fouling on the bonnet lid. There must be a microswitch somewhere to detect the bonnet being open. I'm not used to this level of automation! 5. The wheel arch liner is held in place by about 12 screws with T25 Torx heads, that go into spire nuts. After reassembly, I had two screws left over, and couldn't find where they should go. I think the lighting conditions were the main problem. I'm not going to worry about it - I don't think the liner is going anywhere.