He studied aeronautical engineering at Miles Aircraft's experimental college in Reading, Berkshire, but returned to Dundee and worked as an assistant to comics artist Bill McCail, and learned by studying the work of Alex Raymond, Milton Caniff and Stan Drake. In 1951 he assisted Len Fullerton on his comic strip Dora, Toni and Liz, before creating Jeff Hawke for the Daily Express in 1954. Jordan's friend Willie Patterson came aboard as writer in 1956, and Jordan wrote the later strips himself. The series has been reprinted all over Europe. After Jeff Hawke finished, Jordan created another science fiction strip, Lance McLane, which ran in the Scottish newspaper the Daily Record from 1976 to 1988.
In the mid seventies Sydney produced the one shot Hall Star for the Dutch comic strip weekly Eppo, which he didn't complete until the mid eighties. It was published in 1987 and 1988 as Stranded on Thyton.