The campaigning editor, whose paper this week devoted 15 pages to the fight to save the Freedom of Information Act, is stepping down after 11 years in the role.
Announcing his departure, managing director Chris Moore praised Simon for his “robust” campaigning and for maintaining “the highest editorial standards.”
Simon joined Newsquest in 1997 as editor of the Advertiser and moved to his current role in 2004.
The announcment of his departure concludes an eventful week at the paper which has also seen it reveal that Prime Minister David Cameron had complained about public spending cuts in his constituency.
Simon told HTFP: “I’ve been around journalists and newsrooms since I was 20 and it’s going to be very strange when that ends. But it is time to go after almost 12 years in Oxford and 21 as an editor.
“There is a tremendous team of talented, resilient people here producing some great local journalism and I will miss them more than anything. It has been such a motivation and inspiration for me to work with them. I’m a very lucky editor.”
Chris said in a statement: “Simon leaves with my gratitude and best wishes after guiding the editorial department through some challenging times.
“He has done so while striving to maintain the highest editorial standards, recruiting and developing an array of tremendous talent and ensuring that our publications campaign robustly and tirelessly on behalf of the communities they serve.
“I would like to take this opportunity to thank Simon for his contribution over the years and wish him well for the future.
“An announcement on his successor will be made in due course.”