// ==UserScript==
// @name           Alan in Lisburn
// @namespace      http://martian.org/marty/greasemonkey/
// @description    Alan is not in Belfast any more
// @include        http://alaninbelfast.blogspot.com/*
// ==/UserScript==

var texts = document.evaluate(
    "//div[@id='header']//text()[contains(normalize-space(.), 'in Belfast')]",
    document, null, XPathResult.UNORDERED_NODE_SNAPSHOT_TYPE, null);

for (var i = 0; i < texts.snapshotLength; ++i) {
    var a = texts.snapshotItem(i);
    a.nodeValue = a.nodeValue.replace(/in Belfast/, "in Lisburn (not Belfast)");
}