Great Britain 1840 1d Mulready Envelope (Forme 3, Stereo A160), SGME2Great Britain 1840 1d Mulready Envelope (Forme 3, Stereo A160), SGME2. Fine used example sent from Dover to Walworth, cancelled contrary to regulation in Dover by a red Maltese Cross to the right of Britannia. Upon arrival into the London post it was additionally cancelled over Britannia with an experimental black Maltese Cross. Backstamped in Dover and London for SP. 17 & 18. 1840. Unusual pre printing paper crease at right and some peripheral