Robert A Siegel held its second sale of the week on Wednesday, with a sale of rare stamps including the philatelic collection of John Thomas.

The 173 lot auction United States Post Offices in China always seemed to have a pair of lots which were likely to rise to the top of the sale: two individual stamps, both unattached though one cancelled, and sporting the famous 1922 $2 on $1 double surcharge.

The error occurred at the US Postal Agency in Shanghai. In the run-up to New Year's Eve 1922 - when the office was scheduled to be closed down - a doubling of the surcharge mark of $2 was applied to a limited number of $1 stamps.

It is believed that the Deputy Postal Agent, Mr E H Murray, knew of the error, but decided that it was not worth complicating his upcoming retirement date over and let it pass into use anyway.

US Post Office in China Double Surcharge Error (sold for $9,500) (Click to enlarge)

In the New York sale, the uncancelled example had the fresher paper and better margins (not so slim on the left), and was offered with an estimate of $8,500 whilst the other was set at $8,000.

In the event, both marginally beat their expectations. The cancelled example was taken away for $8,500 whilst the uncancelled brought $9,500. Another success for Chinese collectibles - though hardly the most spectacular we've seen.

Those interested in collecting and investing in valuable stamps can now look forward to the Bill Gross auction at Spink Shreves.