The new office is likely to cost more than �10m

The relocation will bring more than 400 jobs to the town and unite more of the Trust's operations under one roof - hopefully by Summer 2005.

Planners gave the �10.5m scheme - on the town's historic Great Western Railway site - the go-ahead at a meeting on Tuesday night.

The brownfield site allows the Trust to create a building able to accommodate its central staff and create a National Trust shop and restaurant.

Offices in Cirencester, Melksham and Westbury are due to close while the organisation's base in central London will be replaced with a smaller office.

The Trust said all staff had been offered the opportunity to relocate to the new headquarters.

The Great Western Railway works closed in 1986 after 143 years of operation.