// Takes and landranger grid reference and opens the relevant streetmap.co.uk page
function osref(ref){
var re1 = / /;
ref = ref.replace(re1,"");
var re2 = /^\w\w\d\d\d\d\d\d$/;
if (re2.test(ref))
	{
	var url = "http://www.streetmap.co.uk/streetmap.dll?LRgrid2map?grid=" + ref + "&zoom=3&arrow=Y";
	window.open(url);
	}
else
	{
	window.alert("Sorry, the grid reference " + ref + " is not valid.");
	}
}