Work starts this month on the phased redevelopment of the West Sussex school while the school remains fully operational.

The main element is a new 9,300 sq m three-storey teaching building on land south of the existing campus.

Pupils and staff will move into the new block before existing buildings are demolished.

Bouygues will also refurbish the 1,500 sq m Young Building and deliver five multi-use games areas, landscaped recreation space and a new car park.

The redevelopment will increase capacity from around 1,410 pupils to 1,500 when completed in late 2029.

Facilities will include an assembly hall, sixth-form hub, library and specialist teaching spaces.

The building is targeting BREEAM Excellent and will feature rooftop solar panels, a ground-source heat pump and passive ventilation.

Bouygues UK managing director Mark Cesenek said: “Holy Trinity is exactly the kind of project we do best — complex, phased, delivered on a live site.”