Complex sentence: Two earlier developments in Fleet involved a double opening on 10th May 1991, the Hart Shopping Centre, which was opened officially by HRH The Duchess Of York and the Hart Leisure Centre on Hitches Lane (towards Church Crookham).
Split into simpler sentences: Two earlier developments in Fleet involved the opening of a new shopping centre, the Hart Shopping Centre, which was opened officially by HRH The Duchess Of York in 1991. On the same day, she attended the opening of the Hart Leisure Centre on Hitches Lane (towards Church Crookham).