Eddie Turnbull first spotted Henning Boel playing for Washington while Aberdeen were on their exhaustive tour of the USA in 1967. Just over a year later the Aberdeen manager signed the Danish defender and took him to Pittodrie in November 1968. Although Aberdeen were well served at right back with Jim Whyte established in the side, Henning was equally at home in the centre of defence; his giant frame belied a searing pace. Turnbull was always the innovator and he was keen to see his full backs play a far more positive role and it was perhaps the first time that Pittodrie had witnessed an over lapping full back as they were known.
Boel fitted the requirements well as his powerful running and ability to recover were his strongest assets. Henning made his debut for the first team against Dundee Utd at Tannadice on 4th January 1969. Aberdeen had been struggling on the back of heavy defeats against Dunfermline and Hibernian and Boel made an immediate impression in the side. As the great defence of 1970 took shape it was Boel who was the regular right back with Tom McMillan and Martin Buchan protecting Scotland keeper Bobby Clark. Boel played his part in the 1970 Scottish Cup Final, as he stood firm against the imposing John 'Yogi' Hughes then the more subtle skills of Jimmy Johnstone as Celtic piled on the pressure. He to was kept in check as Boel enjoyed his finest hour in the red of Aberdeen
Later that year Aberdeen embarked on a British record 12 games without conceding a goal and it was Boel who was fast approaching cult status with the Aberdeen support who loved his approach to the game and never-say-die attitude. Boel's career effectively came to an end after suffering ligament damage in a UEFA Cup tie in Germany in 1972 and he never fully recovered after a long lay off. Known by many as the first 'great Dane' to grace Pittodrie, Henning returned to his native Denmark in 1974 after 150 appearances and four memorable goals for the Dons.