I would like to show you an example of this underprint on a stamp but, as yet, I have been unable to locate one.
This underprint is believed to be for the firm Joseph Travers & Sons. They were Wholesale Grocers, Wine and Spirit Merchants.
They operated from:
119 Canon Street,
44 Stanley Street,
3 Pall Mall,
They were not confined to the UK however as the following picture illustrates:
1864. Unofficial overprint type 56 (over the gum) in red.
PP192 1d lake-red (SG 43 or G1)
This underprint has only been found unused.