Ditto the old Chivers jam factory in Histon, and the suburban gardens at Mount Pleasant. A few miles out of town a new 'research park' has risen from a gravel pit, and its first units were let before the water had been drained from the site. Marshall called it the theory of 'industrial districts'. Such districts enjoy the same economies of scale that only giant companies get. Specialised suppliers arrive.
Skilled workers know where to come to ply their trade.
And everyone involved benefits from the spillovers of specialised knowledge. Several are already billion-dollar companies. As the second-rank companies move into that league, the attractiveness of the cluster will increase, and with it the pressures that are choking the city to death. As we reported, the local authorities seem paralysed by the Cambridge phenomenon, like rabbits caught in the headlights. Marshall would probably counsel them to do nothing, on the grounds that the feedback loops in the system will solve the problem in time.