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 established themselves in the old second division and participated in cup matches two times: once reaching the quarter-finals in 1972 and again in the semis of 1978. In both instances, Orient defeated Chelsea but were ultimately eliminated by Arsenal.