Where are you in the country Alistair. You can go into your personal profile and show us.
No need to take the male flowers off - they're needed for pollination. I just remove flowers that are spent.
Your courgettes are probably rotting because they haven't been pollinated. Has the weather been good? Are the bees buzzing about them?
If you're short of pollinators you can do it yourself by going round all the flowers and giving them a tickle in the middle with a little artists paint brush - but they'll probably do it themselves when the weather is warm and dry. Good luck.

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