Douglas Hartree of Manchester University brought Bush's design to England, where he constructed his first "proof of concept" model with his student, Arthur Porter, during 1934. As a result of this, the university acquired a full scale machine incorporating four mechanical integrators in March 1935, which was built by Metropolitan-Vickers, and was, according to Hartree, " first machine of its kind in operation outside the United States". During the next five years three more were added, at Cambridge University, Queen's University Belfast, and the Royal Aircraft Establishment in Farnborough. One of the integrators from this proof of concept is on display in the History of Computing section of the Science Museum in London, alongside a complete Manchester machine.