Arab-Byzantine, a Byzantine Follis of Constans II, countermarked with monogram on obverse, 3.59g (Goodwin A11). Host coin fair, countermark fine.
Reference: Goodwin, T., 'Countermarking in Seventh Century Syria, Part II: Countermarks from after the Arab Conquest', Supplement to ONS Newsletter 183, 2005
Estimate: £30-40