Shows polygons in google and mapquest set up using exactly the same code (works for other providers too).
var myPoly = new Polyline([new LatLonPoint(50.8019207484434,-0.0556182861328125),
new LatLonPoint(50.8220956356266,-0.0662612915039062),
new LatLonPoint(50.8255657054318,-0.0595664978027344),
new LatLonPoint(50.8340229201368,-0.0580215454101562),
new LatLonPoint(50.8643695308712,-0.0787925720214844),
new LatLonPoint(50.8601438648787,-0.0963020324707031),
new LatLonPoint(50.8602522200727,-0.102310180664062),
new LatLonPoint(50.8667530709446,-0.108833312988281),
new LatLonPoint(50.8704364840913,-0.124111175537109),
new LatLonPoint(50.8696781581186,-0.137157440185547),
new LatLonPoint(50.8682698057244,-0.156211853027344),
new LatLonPoint(50.857868347639,-0.176467895507812),
new LatLonPoint(50.8548341519201,-0.186595916748047),
new LatLonPoint(50.8555927193571,-0.197582244873047),
new LatLonPoint(50.8525583755791,-0.212688446044922),
new LatLonPoint(50.8568930919724,-0.223159790039062),
new LatLonPoint(50.8276259373544,-0.215263366699219),
new LatLonPoint(50.8206858460992,-0.163764953613281),
new LatLonPoint(50.812660079565,-0.110378265380859),
new LatLonPoint(50.8078873482951,-0.0830841064453125),
new LatLonPoint(50.8019207484434,-0.0556182861328125)]);
map.addPolyline(myPoly);