Hamilton military chronograph tritium dial "fab four"

Royal Navy issue (#0552) Hamilton chronograph, full ministry of Defence markings on the case back showing 1972 as year it was supplied. The original dial has been replaced later during its service with a tritium version. Tritium was much less radioactive than the original radium used on the early dials. Often these later dial replacements were used by the engineers working on the nuclear submarines of the time, lowering the risk of any radioactivity would have been crucial therefore making these versions quite rare. The distinctive asymmetrical cases are distinctive to a run of issued watches from four manufactures nicknamed by collectors as  “The fab four”