  We introduce a topological field theory with a Bogomol'nyi structure
permitting BPS electric, magnetic and dyonic monopoles. From the general
arguments given by Montonen and Olive the particle spectrum and mass compare
favourably with that of the intermediate vector bosons. In most, if not in all,
of its essential features the topological field theory introduced here provides
an example of a dual field theory, the existence of which was conjectured by
Montonen and Olive.
