Hi Una,
In my opinion if the flower buds are well developed then watering would not be a risk and would probably facilitate the swelling and opening of the flower buds and release of fragrance. If it is the true D. nobile species (purple labellum blotch with pink tips on sepals), it really will have benefited from the drought period you have provided. If they are heavily fed and watered in the autumn they will produce beautiful plump green stems but will not produce many flowers. The YouTube Channel “Brads Orchids” recently discussed D. nobile flowering so you could check that out.