Yup - Tilly's injured herself! She was severely limping on her left front and back leg! This started two days ago after a very chaotic walk which involved her, Betsy, another Labradoodle, Rottweiler, Lurcher, Shih Tzu, Chihuahua and Collie!! I saw her slip in a rather energetic game, but it didn't phase her at the time. Only later on did I see that she was limping.
So I've rested her for a couple of days and apart from driving me crazy through lack of exercise (pacing, barking etc) it seems to be clearing up, which is excellent!

With Tilly on the bench at the sidelines, I've been doing some agility training with Betsy. Turns out she's taken to it quite well - so watch this space!