Quite right, these are originals almost certainly stolen from the PRO by that bastard Graves. The seller probably quite genuinely believes these have good provenance - nevertheless - they belong to the Country.
I will inform the National Archives to see if they want to pursue it further.
I was informed that they were already aware of the items being on sale. The auction was abandoned within 24 hours - I'd like to think it was because of Grovetown's prompt action.