Bill Edgar's Tuesday trivia question

Question: What do the following years have in common in relation to English clubs in European competition: 1968, 1970, 1971, 1981, 1984?

Come back tomorrow for the answer.

Yesterday we asked: Which player scored a winning goal in an FA Cup semi-final in the past 15 years but subsequently played in the United Counties League, five levels below the Football League, when still in his twenties?

Answer: Christopher Wreh. The Liberian striker scored the only goal in Arsenal’s semi-final win over Wolverhampton Wanderers in 1998. Having then played for various other clubs, he joined Buckingham Town in 2004.