Offered by Bennett Stamps. There is no doubt in my mind that the "BOAC / MARINDUQUE" cancel is of the Revolutionary Government period, having seen one on a large official document piece. Based on the appearance of the piece I think this is also a document piece and not a cover piece based on the presence of manuscript text under the cancelled stamps and the  2c x 2 Washington as a form of tax payment. As a revenue collector I have come across early USPI period documents bearing Bureau issues with Revolutionary Government cancels. 

For this to be considered a cover piece the stamps must have been affixed near the center of the envelope and the manuscript under it is the written address. The chances of this being so is very remote.

I do not have an idea on the "POSTAGE DUE" handstamp on the 2c Bureau. During the early days of Ebay a 1c Bureau was offered with the same handstamp but did not bother to seriously look at it since my bidding attention then was devoted to vinyl records.

Could the above be a provisional Postage Due stamp? I hope someone will seriously take a close look on the above. I know the answer is out there waiting to be discovered.