Early Minis had a two-piece radiator housing with upper and lower sections. The radiator was held in place by screws that passed through the housing into the side frame of the radiator. The radiator frame had three (3) clips on each side, and these special screws were tightened into the clips. Screws are sold each.
Clip is GHF0713, sold each.
These screws and clips were used until the one-piece radiator shroud was introduced in the 1970s.