William Dawbarn & Co. were a firm of Timber Merchants trading in Liverpool.
As yet I have been able to find very little information on the firm other than a reference to a publication being:
"...printed at the private printing press of William Dawbarn, Liverpool."
1868. Unofficial overprint type 19 in black.
a) Vertical overprint, reading upwards
b) Vertical overprint, reading downwards
PP58 1d lake-red (SG 43 or G1)
Plate 154 is known unused.
PP58a As PP58 but overprint double.
Used on cover
1873. Unofficial underprint type 20 (over the gum) in black.
a) Vertical underprint, reading upwards
Note. Plate 213 is currently unlisted by Stanley Gibbons with this underprint.
Plate numbers 221 and 223 have been found unused.
b) Vertical underprint, reading downwards
Note. Plate 203 is currently unlisted by Stanley Gibbons with this underprint.