Cross Domain request SharePoint hosted app Office 365 Developer Tools

I am creating some SharePoint hosted apps, and have decided to use Napa Office 365 Developer Tools for ease of setup, and then export the projects to Visual Studio at a later date if required.

I have a problem calling cross domain to retrieve information from a list on the SPHostWeb.

My code is from the folliwing example project

(function () {

    'use strict';

    var user = context.get_web().get_currentUser();

    // This code runs when the DOM is ready and creates a context object which is 
    // needed to use the SharePoint object model
    $(document).ready(function () {
        getHostWebTitle();
    });

    function getHostUrl () {
        var args = window.location.search.substring(1).split("&");
        var spHostUrl = "";
        for (var i = 0; i < args.length; i++) {
            var n = args[i].split("=");
            if (n[0] == "SPHostUrl")
                spHostUrl = decodeURIComponent(n[1]);
        }
        return spHostUrl;               
    }

    function getAppWebUrl () {
        var appWebUrl = "";
        var args = window.location.search.substring(1).split("&");
        for (var i = 0; i < args.length; i++) {
            var n = args[i].split("=");
            if (n[0] == "SPAppWebUrl")
                appWebUrl = decodeURIComponent(n[1]);
        }
        return appWebUrl;
    }

    // Get Host web title
    function getHostWebTitle() {
        var spHostUrl = getHostUrl();
        var appWebUrl = getAppWebUrl();

        //Load Libraries
        var scriptbase = spHostUrl + "/_layouts/15/";
        var list = "Links";     

        jQuery.getScript(scriptbase + "MicrosoftAjax.js").then(function (data) {
            return jQuery.getScript(scriptbase + "SP.Runtime.js");
        }).then(function (data) {
            return jQuery.getScript(scriptbase + "SP.js");
        }).then(function (data) {
            return jQuery.getScript(scriptbase + "SP.RequestExecutor.js");
        }).then(function (data) {

            var executor = new SP.RequestExecutor(appWebUrl);
            executor.executeAsync(
                    {
                        url:
                            appWebUrl +
                            "/_api/SP.AppContextSite(@target)/web/lists/getByTitle('" + list + "')/items?$select=Title&@target='" +
                            spHostUrl + "'",
                        method: "GET",
                        headers: { "Accept": "application/json; odata=verbose" },
                        success: function (data) {
                            console.log('success');
                        },
                        error: function (data) {
                            console.log('fail');
                        }
                    }
                );

        });
    }   

}());

My code follows all the way through to the executor.executeAsync request, however comes back with the following error: value: "Access denied. You do not have permission to perform this action or access this resource."