Marks earned his first European Tour start at the 1981 Martini International and made his first cut a month later at the Greater Manchester Open, aged seventeen and still an amateur.

[2] In 1994, upon visiting relatives of his future wife in Poland, it just so happened that the Polish Open were on the same week.

Marks joined and went on to win it, in the process earning a spot at the 1995 and 1996 Sarazen World Open, an unofficial PGA Tour event held near Atlanta, Georgia where winners of national open golf championships around the world were invited to play.

[1] In 2006 he won the Open de Neuchatel on the Alps Tour, as well as the inaugural PGA Play-offs at Woodhall Spa.

He nearly captured a second title the following year at the Sharjah Senior Golf Masters, losing a playoff to Chris Williams.