A mobile barrier was first used at Harold Park, New South Wales track on 2 November 1956 in a mile race won by Mineral Spring in 2:01.2. However the barrier was deemed unsafe after two races and it took a further 9 years before further attempts were made. The prototype hydraulically operated mobile barrier was introduced into NSW in 1963 by William (Bill) George Smith, a Sydney motor body builder who had a passion for harness racing and wanted to make it more exciting for the public and punters. On 14 October 1970 in an article on the success of the Miracle Mile the Sydney Morning Herald reflected on the introduction of new barrier in 1965. The article stated that after months of testing the barrier at Sunday gymkhanas, shows and trials during 1964 and 65 it was then decided to introduce the barrier at Harold Park. Harold Park trialled and approved the use of the Smith designed barrier on 21 May 1965. 'Late in 1966 The New South Wales Trotting club Ltd and H O & W D Wills promoted a new feature race call the Craven Filter Miracle Mile'. the idea was to break the two minute mile and for Australian horses to gain worldwide recognition. The first Miracle Mile was held at Harold Park in 1967 and the New Zealand mare Robyn Dundee won by breaking the two minute barrier at 1:59.