The ban was primarily put in place as a response to the growing number of English players being recruited by Australian clubs.
John Player Trophy Winners were Warrington beating Widnes 9-4 in the final Rugby League Premiership Trophy Winners were Bradford Northern beating Widnes 17-8 in the final.
BBC2 Floodlit Trophy Winners were Hull Kingston Rovers beating St. Helens 26-11 in the final.
Leeds beat St Helens 14-12 in the final played at Wembley Stadium on Saturday 13 May 1978 before a crowd of 96,000.
This was Leeds’ eleventh Cup Final win in fifteen appearances and their second in successive years.