In this paper we discuss how we have introduced elements of diversity in the experimental model driven development process of a railway signalling system. The experience has been done inside a larger industrial project undertaken to evaluate the feasibility of employing formal modelling and automatic code generation in the development of a new generation of railway signalling systems hosted by an innovative fault-tolerant platform. Diversity has been introduced where an analysis of the safety measures employed against design faults has revealed possible weakness of the development process.