18th CENTURY LETTERPRESS?????

I believe this may date from 1715 - 1820 it is a letterpress used for book illustrations . It was rescued from a skip at the Clarendon Building in Broad Street Oxford and depicts typical 18th century rural folk with a cart drawn by a single ox.
The Clarendon Building was home to Oxford University Press from 1715 until 1820 when they moved to their present location Walton Street Oxford the inscription on the wood block the press is mounted on has the inscripton "2 and G1R" (George 1 1714 - 1727)
This is all my research so far as I am having difficulty verifying authenticity. Oxford University Press, The curator of rare books at the Bodleian Library and the National Print Museum in Dublin could offer no assistance, however the Secretary of the bookplate society in London states in his reply that it is feasible that this could date from the early 18th century but as yet this has to be confirmed. Despite an exhaustive on line search I have not been able to source the illustration. I took it to the Forestry Department at the Unniversity of Oxford recently and a Professor in the department has identified the wood block as an African Mahogany and estimates a date of 1790 to 1820.