Ben, an articulate 14-year-old hard at work in the school design and proto-typing centre, is explaining to Lord Baker of Dorking how 3D printing works. Baker, a former Tory education secretary, listens intently before declaring the technology ‘marvellous’. This coming July will mark the 25th anniversary of his leaving the Department for Education — but Lord Baker, who turns 80 this year, has never quite stopped the school reform that he started.