It's good to know that even a 'Master of Letterpress' sometimes forgets to put the paper in the press and gets the image printed all over the blanket on the roller. It seems to have happened several times too, even at Tilley Printing, so that cheers me up even more, sorry Martin!
The big bonus of the happy accident is the fact that a beautiful image slowly builds up on the blanket, serendipity you might say.
No matter what, when the blanket is replaced don't throw it away, get it framed.
Better still, send it to West Norfolk and I'll get it framed!