Watch List notes:

Mary, bawbee, first period 1542 – 1558, group 3, class VI ai, crowned thistle dividing MR, crown of three larger and two smaller lis, MARIA DG R[EGINA SCOTO]RVM, rev. voided saltire cross through crown, cinquefoil each side, inverted cross/crown (very rare die), OPPIDVM EDI[NBVR]GI, wt. 1.78gms (S.5433), fine, very rare
*ex Andrew Howitt, 12/02/2009, purchased for £85
Not as such in Burns, but class VI
For a similar reverse example in Lord Stewartby Collection – BNJ 1989, vol. 59, pp. 120 – 156, plate 14, no. 86 – 87
None with inverted cross in SCBI vol. 35 or vol. 58

Estimate: 75 - 100 GBP