The Small Trail Plate was issued 15 January 1841.  A new fugative ink was introduced for this denomination in 1841 and horizontal lines were added to the top below "POSTAGE" and at the bottom above the value tablet.  It was necessary to send specimens of the new stamp design along with an official notice to the post offices.  However,  stamps based upon the new design were not yet ready.  Therefore a small plate of 12 impressions was made to fill this requirement.   It should be noted that check letters were not used and the check letter squares are empty.  If one examines examples closely it is possible to see what appear to be the guide lines used to guide the laying down of the impressions.  However, from the appearance of the guide lines one can speculate that the process was rushed in order to make a deadline for distribution of the specimens.  The impressions are not well placed in conjunction with these guidelines.  Interestingly enough,  although the stamps are  watermarked small crown this is not mentioned in the Stanley Gibbons  Great Britain Specialized Catalog , Vol. 1, Queen Victoria, 10th Ed.
 
 

Detail of guide lines