In 2012 Michael Eldon (formerly Michael Einhorn) sent us 
photographs of a school trip to Kew Gardens.  
He thinks the year was 1947 and that the teachers were
Miss Gould and Mr Miller (though not too sure about the latter.)
The three boys on the seat are John Hillier, Derek ?, and Michael Ward
Michael Eldon took the photographs with his Brownie box camera.