I had an accident like this when i was 20 in my old XR2i.
I was going down a dark lane with a 60mph limit, in front of me was a M3, i figured if i caught the M3 up, i could follow it as i did not know the roads.
10mins later, i went rough a LH bend that had gotten far tighter than expected, it was wet & i touched the brakes. The back end came light, and spun around with the car ending up on the grass verge / road. I was lucky as i went side ways through a stone bridge.
This was put down to -
a) The farmer having mud on the road
b) It being wet
c) The mix & match tyres on the car
d) The idiot behind the wheel
I thought i was cool, and i could drive like that. But infact that day taught me alot about driving on roads i dont know.
Experience is everything..
(The police will just want to know what happened - So you were approaching the bend, tapped the brakes and the car came unstuck, you corrected the steering which the car gripped again and you were off into the grass area).