Had the boat's availability, just when he needed it, been sheer accident?
It was only by the sheerest accident that he had found out, even now; about them.
By sheer accident, he'd hit on a late hour.
And he had, by sheerest accident, slipped through the hands of the priests.
And yet, if it weren't for sheer accident, she would never have been allowed to come here at all.
"And by sheerest accident, I get to be in all the pictures."
And then sheer accident intruded into what had been a very orderly life.
He knew he could only be discovered by sheer accident.
The authors have often had this situation occur, usually by sheer accident.
They'll never be found except by the sheerest accident while in flight.
