The <a href="https://en.wikipedia.org/wiki/Penny_Black" id="mwaA" rel="mw:WikiLink" title="Penny Black">Penny Black</a> <a href="https://en.wikipedia.org/wiki/Postage_stamp" id="mwaQ" rel="mw:WikiLink" title="Postage stamp">postage stamp</a> becomes valid for use in the <a href="https://en.wikipedia.org/wiki/United_Kingdom_of_Great_Britain_and_Ireland" id="mwag" rel="mw:WikiLink" title="United Kingdom of Great Britain and Ireland">United Kingdom of Great Britain and Ireland</a>.