Penny Mulready Envelope used on the 10th of May 1840 1st Sunday only 16 recorded

1840 Mulready One Penny Envelopes A150 dated 10 May 1840 (first Sunday) to London bold red Maltese Cross cancellation in an orange shade on reverse fine Worthing/my 10/1840. Only 16 Penny Envelopes are recorded in May Dates by Mike Jackson. (this item is illustrated on page 302 of May Dates by Mike Jackson. Cat from 16000 pounds.