Up until now I have merrily removed all the male flowers from my courgettes and I have been doing the same for the melons/squashes/gourds/pumpkins. I remembered reading somewhere that if you left them the fruit might get bitter. Doing a bit more reading, so as to figure out how to look after my new additions, I came across the word "monoecious" which derives form the Greek "One House". In botanical terms it means that a plant produces both male and female flowers. Then the penny dropped: by removing all the male flowers there is the risk of making the plant infertile and fruit not setting properly or developing at all. Of course there is little danger of catching every male flower given that the plot is across town and the most I visit it is twice a week, but the couple of extra fig leaf melons I planted out under my nose at home have failed to produce any fruit. Now I think I know why - my over enthusiastic male flower snipping. No longer: now the "non productive" male flowers get to stay as long as they like. Despite all this there have still been quite a number of young fruit that have shown signs of rot and/or dropped off in the recent bout of cold weather.
Dioecious is where each plant produces flowers of just one sex. Examples are Holly, Asparagus and (to my horror) Mulberry trees. This explains why our solitary specimen has failed to produce fruit to date!!! Now I have to figure out which sex it is and order another sex specific tree.
p.s. You get some rather unhelpful results if you Google "How to sex a mulberry bush", but I have discovered that I need to wait until next spring and examine the flowers.