Oops! over 40 years with no claims, then I do this

Reversing using mirrors as usual, obstacle visible on near side, missing that - then Bang! Another obstacle behind the car not visible in either mirror and too low to see through rear windscreen. 
The dogs were all in the back but not hurt - they were in their crate and the rear screen blew outwards so very little glass inside the car. I can't open the back but fortunately the crate has a rear escape when the rear seats are folded down so they were fine.
No one hurt, the only damage is to my car - and not much really - so it could have been worse.