Openlayers 4 WFS & vector select

I want to convert this project for other use from OL2 to OL4 but I can't convert the code and get back a map,

http://www.trafficorders.uk/

here the OL2 code:

  layer = new OpenLayers.Layer.WMS("UKMap", "http://www.trafficorders.uk/cgi-bin/wmsmaps", {
    layers: "bgmap"
  }, {
    isBaseLayer: true,
    transitionEffect: 'resize',
    singleTile: false,
    ratio: 1.1

  });

  var areaStyMap = new OpenLayers.StyleMap({
    "default": new OpenLayers.Style({
      fill: true,
      fillOpacity: 1,
      strokeColor: "#000000",
      fillColor: "${MapColour}",
      strokeWidth: 1


    }),
    "select": new OpenLayers.Style({
      strokeColor: "#FFFFFF",
      fillOpacity: 1,
      strokeWidth: 2,
      fillColor: "#FF9900",
      label: "${Name}",
      labelOutlineWidth: 3,
      labelOutlineColor: '#ffffff',
      fontSize: "12px",

      fontFamily: "Arial, Courier New",
      fontWeight: "bold"
    })
  });

  var strat = new OpenLayers.Strategy.Fixed();
  var pmproto = new OpenLayers.Protocol.WFS({
    url: "http://www.trafficorders.uk/cgi-bin/mapserv?map=/var/www/vhosts/trafficorders.uk/httpdocs/maps/wfsareas.map",
    featureType: "la_areas",
    featureNS: "http://mapserver.gis.umn.edu/mapserver",

    featurePrefix: "ms"
  });
  arealayer = new OpenLayers.Layer.Vector("la_areas", {
    strategies: [strat],
    protocol: pmproto,
    styleMap: areaStyMap
  });

and here my new code:

var vector = new ol.layer.Vector({

  source: new ol.source.Vector({
    url: 'http://www.traffwebdev.uk/cgi-bin/mapserv?map=/var/www/vhosts/traffwebdev.uk/httpdocs/hosted/maps/wfsareas.map',
    format: new ol.format.WFS({
      featureType: ["la_areas"],
      featureNS: "http://mapserver.gis.umn.edu/mapserver",
      featurePrefix: "ms"
    })
  })
});

the featureNS seems to do not works, I don't have nothing back while in the old code I have a collection of features.

What I want to achieve is something like this but with WFS instead of geoJson

https://openlayers.org/en/latest/examples/box-selection.html

Answer

You will find 2 solutions:

Normally according to the current code you should use the first solution e.g with map projection EPSG 27700 (surely related to the fact that your map is UK only)