A former Perth school traffic warden accused of sexually assaulting a child and possessing more than 26,000 child exploitation images will walk free until he faces trial, a WA judge has decided on Monday.

Michael Cyril Hyde, 59, was charged with more than 300 child sex-related offences after his arrest two years ago.

Police are alleging the abuse spanned a period of six years and came to light after an investigation by the Joint Anti Child Exploitation Team.

Mr Hyde was granted bail by Judge Simon Stone on Monday after concerns were raised by the 59-year-old's defence team at the length of time he had already spent in custody awaiting trial.