He has now posted pictures of the stamps on his blog.
This got me thinking about the two NVIs issued for the weight steps on the Special Delivery service stamps which were issued on 26th October last year. These also carry the year date MA10, but as they are sheet stamps there is no source code.Images below are courtesy of Norvic Philatelics
The stamps were printed by De La rue in gravure. With a initial high value of £5.05 and £5.50 respectively. After the price increase on 4th April 2011 the new rates are now £5.45 and £5.90.
Due to the high cost of these stamps I do not think stocks will dwindle in a hurry so I personally do not envisage a new code of MA11, or perhaps MA12 will materialise. I could be wrong so I will give Larry the chance to recover his losses, my bet is a 2p used Machin.
Larry wrote about these two stamps whilst I was away, I do not think he mentioned the codes in his report.