Complex sentence: Industry was slow to develop in the area, as in most of what would become Trafford, partly because of the reluctance of the two main land owners in the area, the Stamfords and the de Traffords, to invest.
Split into simpler sentences: Industry was slow to develop in the area, as in most of what would become Trafford. This was partly because of the reluctance to of the two main land owners in the area, the Stamfords and the de Traffords, to invest.