Whats going on with my courgette

It's called mosaic virus and courgettes can suffer quite badly if you are unlucky. Try buying a resistant variety next year, as there are many available.

Thank you Bertiefox, is it in the plant or in the soil, I run a system of raised beds so don't want to see it spreading , if in the soil can it be sterilised/killed or not (will have to google it later) thanks very much for your quick answer this ones going in the wheelie bin then!!

This is some info on mosaic virus I found on an American website. In essence, the only cure is to tidy up the diseased plants and burn or bin them (as you are doing), though getting seed of a resistant variety is probably the best thing to do. It's strange how this year we had only one plant out of about twenty (courgettes, squashes, melons) affected.

"Mosaic virus is caused by a variety of viruses which attack all members of the curcurbit family, but especially thrive on summer squash, cucumber and melon plants.
Mosaic virus damage first appears in the form of green leaves which look as if they are mottled or distorted. Often these leaves will also be curled upward, or appear as if their growth has been stunted. Typically these leaves will have yellowish spot on them, adding to their mottled appearance. If cucumber fruits are affected they will vary in color from light green to dark green mottled areas and some which pale to white. Affected areas of the curcurbit family plants may also be covered with warts or alternately the skins may be have faded and be very white and smooth.

Mosaic virus overwinters on a variety of plants including debris from curcurbit family plants which was not cleared from the garden. Aphids spread the disease as they feed going from infected plant to healthy plant. The prevalence of these insects once they have infested a garden can be damaging on its own, not to mention when these insects are spreading mosaic virus. The earlier in the season the disease is spread, the more plants will have severe damage from mosaic virus. "

Thanks again bertiefox, youre a star!