The O's became established in the old second division and enjoyed two cup runs, to the quarter-finals in 1972 and the semis in 1978. On both occasions Orient defeated Chelsea en route and were finally eliminated by Arsenal.
The O's became prominent in the old second division and participated twice in cup competitions, reaching the quarter-finals in 1972 and the semis in 1978. In both instances, Orient defeated Chelsea on their way to elimination by Arsenal.