Caterpillar problem

Hi people. Caterpillar identification please? They are in abundance and eating everything that the snails don't get. What is the best way to deal with these perils? Thanks in advance.

 

Thanks for that JKW. I have a cage for my Veg. It's only about 12 mm mesh but they still slip through ok but can't seem to find their way out. Ha ha! I have to lift the netting to let them out again. I have quite a variety of butterflies this year, hence the question. The trouble is they are eating all my young flowers too. I love butterflies and enjoy photographing them but my plants are being wrecked this year. Thanks for your response. Much appreciated.

 

Caterpillars love Nasturtiums Rustler, perhaps next year you can plant some of those as a distraction.