Just set about doing my 103 piece double sided jigsaw of the Charles II "petition crown" that has been published by the London coin dealers Spink & Son. I got to the end (well really just past the beginning) to find that one piece of the border was missing at the top!
Of the 14 "petition crowns" that are known to exist only three are in private hands, nine are in museums and two are unaccounted for.
The coin they have used is the specimen owned by Geoffrey Cope, the finest known example. He is the collector who has also lent an absolutely superb example of the EXERC BRITANNICVS coin of Hadrian to the British Museum.
There is also an absolutely superb sestertius of Agripina Senior in his collection.