Horn became a clerk with the textile firm Lehmann & Co, and became an amateur referee, after his playing career was ended by a knee injury.

[2] The next September Horn refereed the playoff of the 1962 Copa Libertadores Finals after the original two-legged tie ended in a draw.

Toward the end of his career Horn was appointed to referee the Leeds United v Valencia match in the Inter Cities Fairs Cup on 2 February 1966.

Of this game, Jack Charlton said: "One of the greatest storms in European football burst about the heads of Leeds United when they played Valencia.

I was in the centre of the row – three players, including myself, were ordered off; both teams were also summoned from the field for a spell to allow heated tempers to cool" Horn claimed: 'Money was the cause of the trouble.