I can see you reasoning but first of all I doubt that the ordinary folk in Newcastle were switched on to Christian Dior's New Look(my Mum certainly wasnt) and were still battling with the privations which followed the war years and the strict rationing of clothing which they endured until 1949 and which restricted the amount of new clothing they could buy.
So for various reasons I stick with 1948 to March 1950 with my best bet being 1949.