You wouldn't believe it, but it's happened again.
This time my 18month old got hold of my camera and dropped it, with no case about 30-50cm onto the floor (thankfully with carpet) and smashed the UV filter on the front of my new Sigma 28-70mm f2.8 lens. So that's another new filter needed and a 77mm one at that, which is a bit more expensive than the 49mm on the other lens. Grr.
Thankfully the lens is fine.