Theobald, appointed alongside Nightingale in October 2015, guided the club to a 4-1 away win at Romford on Saturday before resigning four days after Nightingale left last Wednesday to take over at Cambridge City in the Evo-Stik League Southern.
In a statement announcing Theobald's departure to join Nightingale at City where they were both fans' favourites as players, officials set a deadline of Sunday 11 December for potential successors to send a covering letter and their footballing CVs to Soham Town Rangers chairman Stuart Hamilton.
A spokesman said: "The successful candidate will take full responsibility for all on-field football activities for the first team, who play in the Ryman Isthmian League Division One North, as well as having an overview for the club’s reserve side in the Cambridgeshire County League.
"We are looking for an ambitious manager who will be able to demonstrate their knowledge of Non-League football at Step Four and help us to progress to the next level whilst keeping within agreed budgets."
Theobald and Nightingale, pictured, succeeded Steve Fallon and saved the club from relegation in their first season at the helm. After thanking Nightingale for their efforts last week, Theobald also left at the weekend with the club's best wishes despite officials regretting both departures.
The spokesman added: "It is with regret that Soham Town Rangers confirm that David Theobald has left the club. The club wish to thank David for all his hard work since he arrived and wish his well for the future."
Senior players Will Lawton and Robbie Mason have been asked to look after first team affairs, starting with Aveley at home on Saturday.
Image courtesy of Soham Town Rangers
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