Yesterday morning lots of potatoes on our site frosted and beans, sweetcorn, tomatoes and squashes (what are people doing planting them out so early!). The temp in the closed coldframe had been 4 degrees.
Mine are OK so far. It seems quite random which catch the frost and which don't, sometimes just one plant in a row, sometimes one end etc. My plot neighbour a few feet away has some scorching and I don't.