I have a very large cover, measuring 12 by 5 inches, sent registered airmail to the US, postmarked 17 July 1970. The cover is franked with a 10p and a 5/- Machin, total franking of 7/-.
My read of the tables is that registry was 3/-, leaving 4/- to be accounted for. The 1oz rate was 3/- and the next step would be 4/6 which would put me 6d over.
I have attached an image and as you can see there are no other markings or labels, so no insurance, no express etc etc.
Any thoughts on how to make the franking work? FYI the sender was the National Provincial Bank, Ltd, the recipient being the Camden Trust Company. I doubt there was a stamp collector in the background looking to make a good cover.
Was there some other fee I am not accounting for?
Your help would be appreciated.
best,
Larry
![Image](http://i.imgur.com/q2K840Y.jpg?1)