Just once, with the #2 prototype Commando. I was riding on rural roads that I thought I knew well, but I mis-remembered where I was. I came over a hump-backed bridge over a canal where I expected a long sweeping right-hand turn on the other side. Unfortunately, that bridge was 2 miles further down the canal. As I went almost weightless over the bridge, I was faced with a T-junction!
I went through a hawthorn hedge into a pasture and was able to U-turn back to the field gate. The only casualty was my Barbour riding suit, which suffered a few rips from the thorns of the hedge.