This inevitably of those stupid questions BUT

Not a stupid question New at this... sounds like greenbottle flies, have a good look round and see if you can find a dead mouse or bird that they could be breeding in. Your fruit and veg. isn't what is attracting them, they feed on carrion and excrement. If they been wandering on your food crops do wash them well before eating or cooking.

I like to refer to the color as metallic green. These are green bottle flies ,aka, green blowflies. The adults are attracted to nectar and the smell of carrion so you either have something in flower or something that has died or some kind of animal feces. Now you didn't ask for it but this particular file or rather it's larvae are used in forensic examination to determine the time of death. Also, in our civil war wounded soldiers from the south were more likely to survive their wounds than the soldiers who fought for the north. The reason is that the southern states had a shortage of bandages so the wounds were left uncovered and that gave the green blow file an opportunity to have its larva debride and clean the wounds. The northern soldiers covered the wounds with bandages more often since they were in good supply and being covered they became badly infected and this resulted in their death. To this day the maggots of these flies have medical uses. I do not think that your question was stupid at all:)

Thanks so much. This makes more sense now. We had to have the foul water drain unblocked last week as tree roots had spilt the liner and we went out to completely overflowed driveway. It was horrible. I'm wondering wether its that ?

Yup, it was that.

Agree... that's what did it!

These "green back flies" play a vital and very necessary role in our ecosystem. They belong to the decomposers and help break down dead biological matter. A healthy plant wouldn't bring the flies, but dead decaying strawberries or courgettes would certainly bring the flies - that's their job. Something could have ffallen from the plant. Of course it could be anything else - dead bird, mouse, cat. Follow the flies and see where they lead you.

The pidgeons get the strawberries way before they can rot and my courgettes are still growing son I rot there either. I think it'll have been my drain - it's sorted now so hopefully they'll go. Thanks for all the help. I certainly don't want the flies !

Can't blame you. Glad you got it sorted.

What a good thing it happened before you went on holiday and not while you were away!

Oh Stergram can you imagine coming home to that!

Rather not think about it...
Have you tried putting a jam jar over ripening strawberries? only practicable if you only have a few but its what my mum always used to do. Put a few slug pellets outside the jar as well...Or net them.

I think I will have to net them to be honest. I've not managed to get to one berry yet ! lol