 The design of the dolos is usually credited to the South African Eric Mowbray Merrifield, one-time East London Harbour Engineer (from 1961–1976).In the late 1990s the claim of Aubrey Kruger gained more prominence.Kruger's claim is that he and Merrifield had considered the shape of concrete blocks to be used to protect East London's extensive breakwaters for the City's non-natural harbour, following a major storm in 1963.