Ormston was born in Yorkshire, England and earned a degree in art and illustration at Leeds University sometime around the mid 1980s. For the following few years he spent his time between playing the drums in various bands, some of which released singles and compilation album tracks (The Silent Scream, The second Coming, This Colossal Youth) and working part-time in a Sheffield comic-book shop with fellow budding artists Nick Percival, Greg Staples and filmmaker Lee Ford. Sometime in 1990 he moved into working full-time as an artist working mainly for Judge Dredd Megazine.
Ormston's dark, thick paints were seen in action on the Judge Dredd strip on numerous occasions, most notably in the Judgement Day and Raptaur storylines. For the Judge Dredd Megazine Ormston also created, with Si Spencer, the comedy strip Harke & Burr, a twist on the notorious grave robbers Burke and Hare. His work can also be seen in the Predator comics for Dark Horse, Lucifer and Books of Magic for DC Vertigo—the most frequent home for his American comics work since his 1995 involvement in various Sandman series and offshoots for the company. One of these efforts, his illustration of the series House of Secrets, was with fellow Predator comics contributor Steven Seagle.
Ormston's most well known work in America is most likely Lucifer, written by Mike Carey, Books of Magic, written by Si Spencer, The Girl Who Would Be Death, written by Caitlin R. Kiernan and published by Vertigo in four issues in 1998. He halso worked on other recent Vertigo series such as Books of Magick, Testament and Northlanders from 2005-2008.
Outside of comics, his other works include a brief spell as character designer for Mainframe Animation where he co-created Dot's Bots with writer Steve Seagle, a proposed 13 episode series that so far has only made it to a 30 minute pilot episode. His Reboot Character design of Daemon can be seen in the TV movie Daemon Rising made in 2001.