Last year, British gold dealer Paul Davis identified a variety on the 2002 proof two pound piece. While both reverse and obverse are identical, the edge milling is different on a small number of pieces. Standard coins have wide edge reeding, while the rare variety has narrow or fine edge reeding. So far, PCGS has graded only two examples, while Paul Davis has identified only fourteen examples after many years of searching. Although the exact number minted is not known, the coin is certainly rare.
Above, an example of the fine edge milling on the 2002 proof two pound.
Above, an example of the wider and more common edge milling on the 2002 proof two pound.