His ideas were not made official until 1752, and it was another 14 years before plans were put into place for a competition to create a design for this new development, to be called the New Town.
It took 14 years for his plan to even be considered for the new development of New Town. 
mnli hypothesis: It took 14 years for his plan to even be considered for the new development of New Town.  premise: His ideas were not made official until 1752, and it was another 14 years before plans were put into place for a competition to create a design for this new development, to be called the New Town.