DP20 - Rainbow Colour trials of May 1840
Note voided corner and no corner letters.
This is from the second trial plate of twelve stamps (see below)
For a larger image of this superb stamp click here
for an example in blue click here
Die engraved by Charles & Frederick Heath
based on sketches by Henry Corbould
based on the Wyon City medal (1837) by William Wyon
For a superb example of the 1841 2d colour trial click here
Second trial plate of twelve stamps (3x4) below
Image source British Postal Museum from the R M Phillips Collection. Vol VIII Pg 6.
The first plate only had three impressions and was probably made in March
1840.
The second plate of twelve impressions was used from May to Nov 1840.
They were used for experimenting in printing ink, cancellation inks, and
papers.
More info on the 1840 Rainbow Colour Trials
For even more Rainbow Trials see Vol VIII of the R M Phillips Collection
For the DP43 2d small plate trial go here