oh dear-- can you see anything like greenfly there were swarms here yesterday, you can find cropsafe sprays or organic controls but you need to identify the pest

Do the flowers look like they have been cut off cleanly at a small swelling on the flower stem, Cooleye? If so, they are probably falling off, rather than being eaten. The cause is probably as simple as lack of pollination. Gently tap the top of the flower clusters every morning, and you will probably see fewer flowers disappearing, and more fruit setting. If the night temperatures are still lower than 15 deg. C, then the pollen may not be growing in the style properly, and you may need to use a tomato set spray, until the weather warms.