The theft took place sometime between 9am yesterday (November 1 and 6.30am today (November 2).
Thieves removed the digger using a flatbed truck and Thames Valley Police is appealing for witnesses who may have seen the bright yellow digger being transported on a truck from the school, heading in either the direction of Bracknell town centre or Ascot.
The digger was the property of contractors working on the school site. It is a three-tonne motorized excavator, CAT 304 CR, with a grabber that is unusual as it has a manual release system.
Anyone who witnessed the digger being moved or with any information regarding its whereabouts, should contact police on the non-emergency number 101.