Stroke of luck é uma expressão usada para falar que algo inusitado e favorável aconteceu a uma pessoa. Ao pé da letra significa 'golpe de sorte' 'muita sorte'.
It was a stroke of luck that we found you.
It was a stroke of luck that we found you.

(Foi muita sorte que você me achou.)
He had exactly the part that I needed so that was a stroke of luck.
(Ele tinha exatamente na parte que eu precisava. Foi muita sorte.)
Meeting my favorite celebrity was a real stroke of luck.
He had exactly the part that I needed so that was a stroke of luck.
(Ele tinha exatamente na parte que eu precisava. Foi muita sorte.)
Meeting my favorite celebrity was a real stroke of luck.
(Encontrar minha celebridade favorita foi realmente muita sorte.)
I had a stroke of luck and found Tom at home.
I had a stroke of luck and found Tom at home.
(Eu tive muita sorte e achei Tom em casa.)