Standing in front of a Banksy screenprint that he estimates will hammer for $450,000 to $650,000 next month, Deutscher and Hackett auctioneers’ senior art specialist Henry Mulholland does not look as happy as he should. Surely it’s a thrill to offer a mint condition, signed and editioned Girl with Balloon, one of the British street artist’s most famous images?

It’s exciting that the Sydney vendor snapped up Girl with Balloon for about $100 in December 2004 from Santa’s Ghetto. This pop-up art store in London and Bethlehem was where Banksy sold some of his work from 2002 to 2007.