I'm never really sure that one counts. It's an odd wee thing, lovely, in a great spot, but of unusual form. It's possible it may once have been something like this: http://www.themodernantiquarian.com/post/72960/lordenshaws_cairns.html

Another possible Northumbrian 4-poster is Whinny Hill:
http://www.megalithics.com/england/whinny/whinmain.htm

Three Kings and Goatstones are the real deal though.