Waders on winter farmland?

Sorry to ask a no pictures-no video question but maybe someone can help.

Last weekend I saw 2 small groups of waders flying over farmland near Cambridge just after sunset. There were about 30 in a group, flying fast with pointed wings, so nothing like lapwing or fieldfare. Their grouping and movement was like starlings but they were white underneath, possibly with dark wing edges and dark on top, maybe brown, maybe black, but they disappeared against the ploughed field when they wheeled towards me and I couldn't see them when they landed. Size was maybe the size of dunlin or redshank but they were a way away so I can't really rell. Any suggestions?